diff --git a/Sources/SwiftDocC/Infrastructure/Diagnostics/ANSIAnnotation.swift b/Sources/SwiftDocC/Infrastructure/Diagnostics/ANSIAnnotation.swift
new file mode 100644
index 0000000000..743e41e3ed
--- /dev/null
+++ b/Sources/SwiftDocC/Infrastructure/Diagnostics/ANSIAnnotation.swift
@@ -0,0 +1,57 @@
+/*
+ This source file is part of the Swift.org open source project
+
+ Copyright (c) 2023 Apple Inc. and the Swift project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+
+ See https://swift.org/LICENSE.txt for license information
+ See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+*/
+
+import Foundation
+
+struct ANSIAnnotation {
+    enum Color: UInt8 {
+        case normal = 0
+        case red = 31
+        case green = 32
+        case yellow = 33
+        case `default` = 39
+    }
+    
+    enum Trait: UInt8 {
+        case normal = 0
+        case bold = 1
+        case italic = 3
+    }
+    
+    private var color: Color
+    private var trait: Trait
+    
+    /// The textual representation of the annotation.
+    private var code: String {
+        "\u{001B}[\(trait.rawValue);\(color.rawValue)m"
+    }
+    
+    init(color: Color, trait: Trait = .normal) {
+        self.color = color
+        self.trait = trait
+    }
+    
+    func applied(to message: String) -> String {
+        "\(code)\(message)\(ANSIAnnotation.normal.code)"
+    }
+    
+    static var normal: ANSIAnnotation {
+        self.init(color: .normal, trait: .normal)
+    }
+    
+    /// Annotation used for highlighting source text.
+    static var sourceHighlight: ANSIAnnotation {
+        ANSIAnnotation(color: .green, trait: .bold)
+    }
+    /// Annotation used for highlighting source suggestion.
+    static var sourceSuggestionHighlight: ANSIAnnotation {
+        ANSIAnnotation(color: .default, trait: .bold)
+    }
+}
diff --git a/Sources/SwiftDocC/Infrastructure/Diagnostics/DiagnosticConsoleWriter.swift b/Sources/SwiftDocC/Infrastructure/Diagnostics/DiagnosticConsoleWriter.swift
index 48d2cab77d..e454323f86 100644
--- a/Sources/SwiftDocC/Infrastructure/Diagnostics/DiagnosticConsoleWriter.swift
+++ b/Sources/SwiftDocC/Infrastructure/Diagnostics/DiagnosticConsoleWriter.swift
@@ -9,6 +9,7 @@
 */
 
 import Foundation
+import Markdown
 
 /// Writes diagnostic messages to a text output stream.
 ///
@@ -18,38 +19,66 @@ public final class DiagnosticConsoleWriter: DiagnosticFormattingConsumer {
     var outputStream: TextOutputStream
     public var formattingOptions: DiagnosticFormattingOptions
     private var diagnosticFormatter: DiagnosticConsoleFormatter
+    private var problems: [Problem] = []
 
     /// Creates a new instance of this class with the provided output stream and filter level.
     /// - Parameter stream: The output stream to which this instance will write.
     /// - Parameter filterLevel: Determines what diagnostics should be printed. This filter level is inclusive, i.e. if a level of ``DiagnosticSeverity/information`` is specified, diagnostics with a severity up to and including `.information` will be printed.
     @available(*, deprecated, message: "Use init(_:formattingOptions:) instead")
     public convenience init(_ stream: TextOutputStream = LogHandle.standardError, filterLevel: DiagnosticSeverity = .warning) {
-        self.init(stream, formattingOptions: [])
+        self.init(stream, formattingOptions: [], baseURL: nil, highlight: nil)
     }
 
     /// Creates a new instance of this class with the provided output stream.
-    /// - Parameter stream: The output stream to which this instance will write.
-    public init(_ stream: TextOutputStream = LogHandle.standardError, formattingOptions options: DiagnosticFormattingOptions = []) {
+    /// - Parameters:
+    ///   - stream: The output stream to which this instance will write.
+    ///   - formattingOptions: The formatting options for the diagnostics.
+    ///   - baseUrl: A url to be used as a base url when formatting diagnostic source path.
+    ///   - highlight: Whether or not to highlight the default diagnostic formatting output.
+    public init(
+        _ stream: TextOutputStream = LogHandle.standardError,
+        formattingOptions options: DiagnosticFormattingOptions = [],
+        baseURL: URL? = nil,
+        highlight: Bool? = nil
+    ) {
         outputStream = stream
         formattingOptions = options
-        diagnosticFormatter = Self.makeDiagnosticFormatter(options)
+        diagnosticFormatter = Self.makeDiagnosticFormatter(
+            options,
+            baseURL: baseURL,
+            highlight: highlight ?? TerminalHelper.isConnectedToTerminal
+        )
     }
 
     public func receive(_ problems: [Problem]) {
-        // Add a newline after each formatter description, including the last one.
-        let text = problems.map { diagnosticFormatter.formattedDescription(for: $0).appending("\n") }.joined()
-        outputStream.write(text)
+        if formattingOptions.contains(.formatConsoleOutputForTools) {
+            // Add a newline after each formatter description, including the last one.
+            let text = problems.map { diagnosticFormatter.formattedDescription(for: $0).appending("\n") }.joined()
+            outputStream.write(text)
+        } else {
+            self.problems.append(contentsOf: problems)
+        }
     }
     
     public func finalize() throws {
-        // The console writer writes each diagnostic as they are received.
+        if formattingOptions.contains(.formatConsoleOutputForTools) {
+            // For tools, the console writer writes each diagnostic as they are received.
+        } else {
+            let text = self.diagnosticFormatter.formattedDescription(for: problems)
+            outputStream.write(text)
+        }
+        self.diagnosticFormatter.finalize()
     }
     
-    private static func makeDiagnosticFormatter(_ options: DiagnosticFormattingOptions) -> DiagnosticConsoleFormatter {
+    private static func makeDiagnosticFormatter(
+        _ options: DiagnosticFormattingOptions,
+        baseURL: URL?,
+        highlight: Bool
+    ) -> DiagnosticConsoleFormatter {
         if options.contains(.formatConsoleOutputForTools) {
             return IDEDiagnosticConsoleFormatter(options: options)
         } else {
-            return DefaultDiagnosticConsoleFormatter(options: options)
+            return DefaultDiagnosticConsoleFormatter(baseUrl: baseURL, highlight: highlight, options: options)
         }
     }
 }
@@ -63,12 +92,12 @@ extension DiagnosticConsoleWriter {
     }
     
     public static func formattedDescription(for problem: Problem, options: DiagnosticFormattingOptions = []) -> String {
-        let diagnosticFormatter = makeDiagnosticFormatter(options)
+        let diagnosticFormatter = makeDiagnosticFormatter(options, baseURL: nil, highlight: TerminalHelper.isConnectedToTerminal)
         return diagnosticFormatter.formattedDescription(for: problem)
     }
     
     public static func formattedDescription(for diagnostic: Diagnostic, options: DiagnosticFormattingOptions = []) -> String {
-        let diagnosticFormatter = makeDiagnosticFormatter(options)
+        let diagnosticFormatter = makeDiagnosticFormatter(options, baseURL: nil, highlight: TerminalHelper.isConnectedToTerminal)
         return diagnosticFormatter.formattedDescription(for: diagnostic)
     }
 }
@@ -79,6 +108,7 @@ protocol DiagnosticConsoleFormatter {
     func formattedDescription<Problems>(for problems: Problems) -> String where Problems: Sequence, Problems.Element == Problem
     func formattedDescription(for problem: Problem) -> String
     func formattedDescription(for diagnostic: Diagnostic) -> String
+    func finalize()
 }
 
 extension DiagnosticConsoleFormatter {
@@ -125,6 +155,10 @@ struct IDEDiagnosticConsoleFormatter: DiagnosticConsoleFormatter {
 
         return description
     }
+
+    func finalize() {
+        // Nothing to do after all diagnostics have been formatted.
+    }
     
     public func formattedDescription(for diagnostic: Diagnostic) -> String {
         return formattedDiagnosticSummary(diagnostic) + formattedDiagnosticDetails(diagnostic)
@@ -165,15 +199,293 @@ struct IDEDiagnosticConsoleFormatter: DiagnosticConsoleFormatter {
     }
 }
 
-// FIXME: Improve the readability for diagnostics on the command line https://github.com/apple/swift-docc/issues/496
-struct DefaultDiagnosticConsoleFormatter: DiagnosticConsoleFormatter {
+// MARK: Default formatting
+
+final class DefaultDiagnosticConsoleFormatter: DiagnosticConsoleFormatter {
     var options: DiagnosticFormattingOptions
+    private let baseUrl: URL?
+    private let highlight: Bool
+    private var sourceLines: [URL: [String]] = [:]
+
+    /// The number of additional lines from the source file that should be displayed both before and after the diagnostic source line.
+    private static let contextSize = 2
     
-    func formattedDescription(for problem: Problem) -> String {
-        formattedDescription(for: problem.diagnostic)
+    init(
+        baseUrl: URL?,
+        highlight: Bool,
+        options: DiagnosticFormattingOptions
+    ) {
+        self.baseUrl = baseUrl
+        self.highlight = highlight
+        self.options = options
     }
     
+    func formattedDescription<Problems>(for problems: Problems) -> String where Problems: Sequence, Problems.Element == Problem {
+        let sortedProblems = problems.sorted { lhs, rhs in
+            guard let lhsSource = lhs.diagnostic.source,
+                  let rhsSource = rhs.diagnostic.source
+            else { return lhs.diagnostic.source  == nil }
+            
+            guard let lhsRange = lhs.diagnostic.range,
+                  let rhsRange = rhs.diagnostic.range
+            else { return lhsSource.path < rhsSource.path }
+            
+            if lhsSource.path == rhsSource.path {
+                return lhsRange.lowerBound < rhsRange.lowerBound
+            } else {
+                return lhsSource.path < rhsSource.path
+            }
+        }
+
+        return sortedProblems.map { formattedDescription(for: $0) }.joined(separator: "\n\n")
+    }
+
+    func formattedDescription(for problem: Problem) -> String {
+        formattedDiagnosticsSummary(for: problem.diagnostic) +
+        formattedDiagnosticDetails(for: problem.diagnostic) +
+        formattedDiagnosticSource(for: problem.diagnostic, with: problem.possibleSolutions)
+    }
+
     func formattedDescription(for diagnostic: Diagnostic) -> String {
-        return IDEDiagnosticConsoleFormatter(options: options).formattedDescription(for: diagnostic)
+        formattedDescription(for: Problem(diagnostic: diagnostic))
+    }
+
+    func finalize() {
+        // Since the `sourceLines` could potentially be big if there were diagnostics in many large files,
+        // we remove the cached lines in a clean up step after all diagnostics have been formatted.
+        sourceLines = [:]
+    }
+}
+
+extension DefaultDiagnosticConsoleFormatter {
+    private func formattedDiagnosticsSummary(for diagnostic: Diagnostic) -> String {
+        let summary =  diagnostic.severity.description + ": " + diagnostic.summary
+        if highlight {
+            let ansiAnnotation = diagnostic.severity.ansiAnnotation
+            return ansiAnnotation.applied(to: summary)
+        } else {
+            return summary
+        }
+    }
+    
+    private func formattedDiagnosticDetails(for diagnostic: Diagnostic) -> String {
+        var result = ""
+        if let explanation = diagnostic.explanation {
+            result.append("\n\(explanation)")
+        }
+        
+        if !diagnostic.notes.isEmpty {
+            let formattedNotes = diagnostic.notes
+                .map { note in
+                    let location = "\(formattedSourcePath(note.source)):\(note.range.lowerBound.line):\(note.range.lowerBound.column)"
+                    return "\(location): \(note.message)"
+                }
+                .joined(separator: "\n")
+            result.append("\n\(formattedNotes)")
+        }
+        
+        return result
+    }
+    
+    private func formattedDiagnosticSource(
+        for diagnostic: Diagnostic,
+        with solutions: [Solution]
+    ) -> String {
+        var result = ""
+        
+        guard let url = diagnostic.source
+        else { return "" }
+        
+        guard let diagnosticRange = diagnostic.range
+        else { return "\n--> \(formattedSourcePath(url))" }
+        
+        let sourceLines = readSourceLines(url)
+
+        guard !sourceLines.isEmpty
+        else {
+            return "\n--> \(formattedSourcePath(url)):\(diagnosticRange.lowerBound.line):\(diagnosticRange.lowerBound.column)-\(diagnosticRange.upperBound.line):\(diagnosticRange.upperBound.column)"
+        }
+        
+        // A range containing the source lines and some surrounding context.
+        let sourceRange = Range(
+            uncheckedBounds: (
+                lower: max(1, diagnosticRange.lowerBound.line - Self.contextSize) - 1,
+                upper: min(sourceLines.count, diagnosticRange.upperBound.line + Self.contextSize)
+            )
+        )
+        let maxLinePrefixWidth = String(sourceRange.upperBound).count
+        
+        var suggestionsPerLocation = [SourceLocation: [String]]()
+        for solution in solutions {
+            // Solutions that requires multiple or zero replacements
+            // will be shown at the beginning of the diagnostic range. 
+            let location: SourceLocation
+            if solution.replacements.count == 1 {
+                location = solution.replacements.first!.range.lowerBound
+            } else {
+                location = diagnosticRange.lowerBound
+            }
+
+            suggestionsPerLocation[location, default: []].append(solution.summary)
+        }
+
+        // Constructs the header for the diagnostic output.
+        // This header is aligned with the line prefix and includes the file path and the range of the diagnostic.\
+        //
+        // Example:
+        //   --> /path/to/file.md:1:10-2:20
+        result.append("\n\(String(repeating: " ", count: maxLinePrefixWidth))--> ")
+        result.append(        "\(formattedSourcePath(url)):\(diagnosticRange.lowerBound.line):\(diagnosticRange.lowerBound.column)-\(diagnosticRange.upperBound.line):\(diagnosticRange.upperBound.column)"
+        )
+
+        for (sourceLineIndex, sourceLine) in sourceLines[sourceRange].enumerated() {
+            let lineNumber = sourceLineIndex + sourceRange.lowerBound + 1
+            let linePrefix = "\(lineNumber)".padding(toLength: maxLinePrefixWidth, withPad: " ", startingAt: 0)
+
+            let highlightedSource = highlightSource(
+                sourceLine: sourceLine,
+                lineNumber: lineNumber,
+                range: diagnosticRange
+            )
+            
+            let separator: String
+            if lineNumber >= diagnosticRange.lowerBound.line && lineNumber <= diagnosticRange.upperBound.line {
+                separator = "+"
+            } else {
+                separator = "|"
+            }
+
+            // Adds to the header, a formatted source line containing the line number as prefix and a source line.
+            // A source line is contained in the diagnostic range will be highlighted.
+            //
+            // Example:
+            // 9  | A line outside the diagnostic range.
+            // 10 + A line inside the diagnostic range.
+            result.append("\n\(linePrefix) \(separator) \(highlightedSource)")
+
+            var suggestionsPerColumn = [Int: [String]]()
+
+            for (location, suggestions) in suggestionsPerLocation where location.line == lineNumber {
+                suggestionsPerColumn[location.column] = suggestions
+            }
+
+            let sortedColumns = suggestionsPerColumn.keys.sorted(by: >)
+
+            guard let firstColumn = sortedColumns.first else { continue }
+
+            let suggestionLinePrefix = String(repeating: " ", count: maxLinePrefixWidth) + " |"
+
+            // Constructs a prefix containing vertical separator at each column containing a suggestion.
+            // Suggestions are shown on different lines, this allows to visually connect a suggestion shown several lines below
+            // with the source code column.
+            //
+            // Example:
+            // 9  | A line outside the diagnostic range.
+            // 10 + A line inside the diagnostic range.
+            //    |   │    ╰─suggestion: A suggestion.
+            //    |   ╰─ suggestion: Another suggestion.
+            var longestPrefix = [Character](repeating: " ", count: firstColumn + 1)
+            for column in sortedColumns {
+                longestPrefix[column] = "│"
+            }
+
+            for columnNumber in sortedColumns {
+                let columnSuggestions = suggestionsPerColumn[columnNumber, default: []]
+                let prefix = suggestionLinePrefix + String(longestPrefix.prefix(columnNumber))
+
+                for (index, suggestion) in columnSuggestions.enumerated() {
+                    // Highlight suggestion and make sure it's displayed on a single line.
+                    let singleLineSuggestion = suggestion.split(separator: "\n", omittingEmptySubsequences: true).joined(separator: "")
+                    let highlightedSuggestion = highlightSuggestion("suggestion: \(singleLineSuggestion)")
+
+                    if index == columnSuggestions.count - 1 {
+                        result.append("\n\(prefix)╰─\(highlightedSuggestion)")
+                    } else {
+                        result.append("\n\(prefix)├─\(highlightedSuggestion)")
+                    }
+                }
+            }
+        }
+        
+        return result
+    }
+    
+    private func highlightSuggestion(
+        _ suggestion: String
+    ) -> String {
+        guard highlight
+        else { return suggestion }
+        
+        let suggestionAnsiAnnotation = ANSIAnnotation.sourceSuggestionHighlight
+        return suggestionAnsiAnnotation.applied(to: suggestion)
+    }
+
+    private func highlightSource(
+        sourceLine: String,
+        lineNumber: Int,
+        range: SourceRange
+    ) -> String {
+        guard highlight,
+              lineNumber >= range.lowerBound.line && lineNumber <= range.upperBound.line,
+              !sourceLine.isEmpty
+        else { return sourceLine }
+        
+        var startColumn: Int
+        if lineNumber == range.lowerBound.line {
+            startColumn = range.lowerBound.column
+        } else {
+            startColumn = 1
+        }
+        
+        var endColumn: Int
+        if lineNumber == range.upperBound.line {
+            endColumn = range.upperBound.column
+        } else {
+            endColumn = sourceLine.count + 1
+        }
+        
+        let columnRange = startColumn..<endColumn
+        let startIndex = sourceLine.index(sourceLine.startIndex, offsetBy: columnRange.lowerBound - 1)
+        let endIndex = sourceLine.index(startIndex, offsetBy: columnRange.count)
+        
+        let ansiAnnotation = ANSIAnnotation.sourceHighlight
+
+        var result = ""
+        result += sourceLine[sourceLine.startIndex..<startIndex]
+        result += ansiAnnotation.applied(to: String(sourceLine[startIndex..<endIndex]))
+        result += sourceLine[endIndex..<sourceLine.endIndex]
+        
+        return result
+    }
+
+    private func readSourceLines(_ url: URL) -> [String] {
+        if let lines = sourceLines[url] {
+            return lines
+        }
+
+        // TODO: Add support for also getting the source lines from the symbol graph files.
+        guard let content = try? String(contentsOf: url)
+        else { return [] }
+        
+        let lines = content.splitByNewlines
+        sourceLines[url] = lines
+        return lines
+    }
+
+    private func formattedSourcePath(_ url: URL) -> String {
+        baseUrl.flatMap { url.relative(to: $0) }.map(\.path) ?? url.path
+    }
+}
+
+private extension DiagnosticSeverity {
+    var ansiAnnotation: ANSIAnnotation {
+        switch self {
+        case .error:
+            return .init(color: .red, trait: .bold)
+        case .warning:
+            return .init(color: .yellow, trait: .bold)
+        case .information, .hint:
+            return .init(color: .default, trait: .bold)
+        }
     }
 }
diff --git a/Sources/SwiftDocC/Infrastructure/Diagnostics/TerminalHelper.swift b/Sources/SwiftDocC/Infrastructure/Diagnostics/TerminalHelper.swift
new file mode 100644
index 0000000000..dc3e33f5da
--- /dev/null
+++ b/Sources/SwiftDocC/Infrastructure/Diagnostics/TerminalHelper.swift
@@ -0,0 +1,25 @@
+/*
+ This source file is part of the Swift.org open source project
+
+ Copyright (c) 2023 Apple Inc. and the Swift project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+
+ See https://swift.org/LICENSE.txt for license information
+ See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+*/
+
+#if canImport(Darwin)
+import Darwin.C
+#elseif canImport(Glibc)
+import Glibc
+#elseif canImport(Musl)
+import Musl
+#elseif os(Windows)
+import CRT
+#endif
+
+enum TerminalHelper {
+    static var isConnectedToTerminal: Bool {
+        isatty(fileno(stderr)) != 0
+    }
+}
diff --git a/Sources/SwiftDocCUtilities/Action/Actions/Convert/ConvertAction.swift b/Sources/SwiftDocCUtilities/Action/Actions/Convert/ConvertAction.swift
index 75635f6d96..8dd40eac6c 100644
--- a/Sources/SwiftDocCUtilities/Action/Actions/Convert/ConvertAction.swift
+++ b/Sources/SwiftDocCUtilities/Action/Actions/Convert/ConvertAction.swift
@@ -149,7 +149,12 @@ public struct ConvertAction: Action, RecreatingContext {
         
         let engine = diagnosticEngine ?? DiagnosticEngine(treatWarningsAsErrors: treatWarningsAsErrors)
         engine.filterLevel = filterLevel
-        engine.add(DiagnosticConsoleWriter(formattingOptions: formattingOptions))
+        engine.add(
+            DiagnosticConsoleWriter(
+                formattingOptions: formattingOptions,
+                baseURL: documentationBundleURL ?? URL(string: fileManager.currentDirectoryPath)
+            )
+        )
         if let diagnosticFilePath = diagnosticFilePath {
             engine.add(DiagnosticFileWriter(outputPath: diagnosticFilePath))
         }
diff --git a/Sources/SwiftDocCUtilities/Action/Actions/IndexAction.swift b/Sources/SwiftDocCUtilities/Action/Actions/IndexAction.swift
index 60d7fc0abd..4fa95d5413 100644
--- a/Sources/SwiftDocCUtilities/Action/Actions/IndexAction.swift
+++ b/Sources/SwiftDocCUtilities/Action/Actions/IndexAction.swift
@@ -1,7 +1,7 @@
 /*
  This source file is part of the Swift.org open source project
 
- Copyright (c) 2021 Apple Inc. and the Swift project authors
+ Copyright (c) 2021-2023 Apple Inc. and the Swift project authors
  Licensed under Apache License v2.0 with Runtime Library Exception
 
  See https://swift.org/LICENSE.txt for license information
@@ -32,7 +32,7 @@ public struct IndexAction: Action {
     private var dataProvider: LocalFileSystemDataProvider!
 
     /// Initializes the action with the given validated options, creates or uses the given action workspace & context.
-    public init(documentationBundleURL: URL, outputURL:URL, bundleIdentifier: String, diagnosticEngine: DiagnosticEngine = .init()) throws
+    public init(documentationBundleURL: URL, outputURL: URL, bundleIdentifier: String, diagnosticEngine: DiagnosticEngine = .init()) throws
     {
         // Initialize the action context.
         self.rootURL = documentationBundleURL
@@ -40,7 +40,7 @@ public struct IndexAction: Action {
         self.bundleIdentifier = bundleIdentifier
 
         self.diagnosticEngine = diagnosticEngine
-        self.diagnosticEngine.add(DiagnosticConsoleWriter(formattingOptions: []))
+        self.diagnosticEngine.add(DiagnosticConsoleWriter(formattingOptions: [], baseURL: documentationBundleURL))
     }
     
     /// Converts each eligable file from the source documentation bundle,
diff --git a/Sources/SwiftDocCUtilities/Action/Actions/TransformForStaticHostingAction.swift b/Sources/SwiftDocCUtilities/Action/Actions/TransformForStaticHostingAction.swift
index d0152ee8dd..6214dd9bac 100644
--- a/Sources/SwiftDocCUtilities/Action/Actions/TransformForStaticHostingAction.swift
+++ b/Sources/SwiftDocCUtilities/Action/Actions/TransformForStaticHostingAction.swift
@@ -40,7 +40,7 @@ struct TransformForStaticHostingAction: Action {
         self.htmlTemplateDirectory = htmlTemplateDirectory
         self.fileManager = fileManager
         self.diagnosticEngine = diagnosticEngine
-        self.diagnosticEngine.add(DiagnosticConsoleWriter(formattingOptions: []))
+        self.diagnosticEngine.add(DiagnosticConsoleWriter(formattingOptions: [], baseURL: documentationBundleURL))
     }
     
     /// Converts each eligible file from the source archive and
diff --git a/Tests/SwiftDocCTests/Diagnostics/DiagnosticConsoleWriterDefaultFormattingTest.swift b/Tests/SwiftDocCTests/Diagnostics/DiagnosticConsoleWriterDefaultFormattingTest.swift
new file mode 100644
index 0000000000..3a68a11550
--- /dev/null
+++ b/Tests/SwiftDocCTests/Diagnostics/DiagnosticConsoleWriterDefaultFormattingTest.swift
@@ -0,0 +1,349 @@
+/*
+ This source file is part of the Swift.org open source project
+
+ Copyright (c) 2023 Apple Inc. and the Swift project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+
+ See https://swift.org/LICENSE.txt for license information
+ See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+*/
+
+import XCTest
+import Markdown
+@testable import SwiftDocC
+
+class DiagnosticConsoleWriterDefaultFormattingTest: XCTestCase {
+
+    class Logger: TextOutputStream {
+        var output = ""
+
+        func write(_ string: String) {
+            output += string
+        }
+    }
+
+    func testSeverityHighlight() {
+        let source = URL(fileURLWithPath: "/path/to/file.md")
+        let range = SourceLocation(line: 1, column: 8, source: source)..<SourceLocation(line: 10, column: 21, source: source)
+        let identifier = "org.swift.docc.test-identifier"
+        let summary = "Test diagnostic summary"
+        let explanation = "Test diagnostic explanation."
+        let expectedPath = "--> /path/to/file.md:1:8-10:21"
+
+        do {
+            let logger = Logger()
+            let consumer = DiagnosticConsoleWriter(logger, highlight: true)
+            let diagnostic = Diagnostic(source: source, severity: .error, range: range, identifier: identifier, summary: summary, explanation: explanation)
+            let problem = Problem(diagnostic: diagnostic, possibleSolutions: [])
+            consumer.receive([problem])
+            try? consumer.finalize()
+            XCTAssertEqual(logger.output, """
+            \u{001B}[1;31merror: \(summary)\u{001B}[0;0m
+            \(explanation)
+            \(expectedPath)
+            """)
+        }
+
+        do {
+            let logger = Logger()
+            let consumer = DiagnosticConsoleWriter(logger, highlight: true)
+            let diagnostic = Diagnostic(source: source, severity: .warning, range: range, identifier: identifier, summary: summary, explanation: explanation)
+            let problem = Problem(diagnostic: diagnostic, possibleSolutions: [])
+            consumer.receive([problem])
+            try? consumer.finalize()
+            XCTAssertEqual(logger.output, """
+            \u{001B}[1;33mwarning: \(summary)\u{001B}[0;0m
+            \(explanation)
+            \(expectedPath)
+            """)
+        }
+
+        do {
+            let logger = Logger()
+            let consumer = DiagnosticConsoleWriter(logger, highlight: true)
+            let diagnostic = Diagnostic(source: source, severity: .hint, range: range, identifier: identifier, summary: summary, explanation: explanation)
+            let problem = Problem(diagnostic: diagnostic, possibleSolutions: [])
+            consumer.receive([problem])
+            try? consumer.finalize()
+            XCTAssertEqual(logger.output, """
+            \u{001B}[1;39mnotice: \(summary)\u{001B}[0;0m
+            \(explanation)
+            \(expectedPath)
+            """)
+        }
+
+        do {
+            let logger = Logger()
+            let consumer = DiagnosticConsoleWriter(logger, highlight: true)
+            let diagnostic = Diagnostic(source: source, severity: .information, range: range, identifier: identifier, summary: summary, explanation: explanation)
+            let problem = Problem(diagnostic: diagnostic, possibleSolutions: [])
+            consumer.receive([problem])
+            try? consumer.finalize()
+            XCTAssertEqual(logger.output, """
+            \u{001B}[1;39mnote: \(summary)\u{001B}[0;0m
+            \(explanation)
+            \(expectedPath)
+            """)
+        }
+    }
+
+    func testDisplaysRelativePath() {
+        let baseURL = URL(fileURLWithPath: "/path/to")
+        let source = URL(fileURLWithPath: "/path/to/file.md")
+        let range = SourceLocation(line: 1, column: 8, source: source)..<SourceLocation(line: 10, column: 21, source: source)
+        let identifier = "org.swift.docc.test-identifier"
+        let summary = "Test diagnostic summary"
+        let explanation = "Test diagnostic explanation."
+
+        let logger = Logger()
+        let consumer = DiagnosticConsoleWriter(logger, baseURL: baseURL, highlight: true)
+        let diagnostic = Diagnostic(source: source, severity: .warning, range: range, identifier: identifier, summary: summary, explanation: explanation)
+        let problem = Problem(diagnostic: diagnostic, possibleSolutions: [])
+        consumer.receive([problem])
+        try? consumer.finalize()
+        XCTAssertEqual(logger.output, """
+        \u{001B}[1;33mwarning: \(summary)\u{001B}[0;0m
+        \(explanation)
+        --> file.md:1:8-10:21
+        """)
+    }
+
+    func testDisplaysNotes() {
+        let source = URL(fileURLWithPath: "/path/to/file.md")
+        let range = SourceLocation(line: 1, column: 8, source: source)..<SourceLocation(line: 10, column: 21, source: source)
+        let identifier = "org.swift.docc.test-identifier"
+        let summary = "Test diagnostic summary"
+        let explanation = "Test diagnostic explanation."
+
+        let logger = Logger()
+        let consumer = DiagnosticConsoleWriter(logger, highlight: true)
+
+        let noteSource = URL(fileURLWithPath: "/path/to/other/file.md")
+        let noteRange = SourceLocation(line: 1, column: 1, source: noteSource)..<SourceLocation(line: 1, column: 20, source: noteSource)
+
+        let diagnostic = Diagnostic(
+            source: source,
+            severity: .warning,
+            range: range,
+            identifier: identifier,
+            summary: summary,
+            explanation: explanation,
+            notes: [DiagnosticNote(source: noteSource, range: noteRange, message: "This is a note")]
+        )
+        let problem = Problem(diagnostic: diagnostic, possibleSolutions: [])
+        consumer.receive([problem])
+        try? consumer.finalize()
+
+        XCTAssertEqual(logger.output, """
+        \u{001B}[1;33mwarning: \(summary)\u{001B}[0;0m
+        \(explanation)
+        /path/to/other/file.md:1:1: This is a note
+        --> /path/to/file.md:1:8-10:21
+        """)
+    }
+
+    func testDisplaysMultipleDiagnosticsSorted() {
+        let identifier = "org.swift.docc.test-identifier"
+        let firstProblem = {
+            let source = URL(fileURLWithPath: "/path/to/file.md")
+            let range = SourceLocation(line: 1, column: 8, source: source)..<SourceLocation(line: 10, column: 21, source: source)
+
+            return Problem(
+                diagnostic: Diagnostic(
+                    source: source,
+                    severity: .warning,
+                    range: range,
+                    identifier: identifier,
+                    summary: "First diagnostic summary",
+                    explanation: "First diagnostic explanation",
+                    notes: []
+                ),
+                possibleSolutions: []
+            )
+        }()
+        let secondProblem = {
+            let source = URL(fileURLWithPath: "/path/to/file.md")
+            let range = SourceLocation(line: 12, column: 1, source: source)..<SourceLocation(line: 12, column: 10, source: source)
+
+            return Problem(
+                diagnostic: Diagnostic(
+                    source: source,
+                    severity: .warning,
+                    range: range,
+                    identifier: identifier,
+                    summary: "Second diagnostic summary",
+                    explanation: "Second diagnostic explanation",
+                    notes: []
+                ),
+                possibleSolutions: []
+            )
+        }()
+
+        let thirdProblem = {
+            let source = URL(fileURLWithPath: "/path/to/other/file.md")
+
+            return Problem(
+                diagnostic: Diagnostic(
+                    source: source,
+                    severity: .warning,
+                    range: nil,
+                    identifier: identifier,
+                    summary: "Third diagnostic summary",
+                    explanation: "Third diagnostic explanation",
+                    notes: []
+                ),
+                possibleSolutions: []
+            )
+        }()
+
+        let logger = Logger()
+        let consumer = DiagnosticConsoleWriter(logger, highlight: true)
+
+        consumer.receive([firstProblem, secondProblem, thirdProblem])
+        try? consumer.finalize()
+        XCTAssertEqual(logger.output, """
+        \u{001B}[1;33mwarning: First diagnostic summary\u{001B}[0;0m
+        First diagnostic explanation
+        --> /path/to/file.md:1:8-10:21
+
+        \u{001B}[1;33mwarning: Second diagnostic summary\u{001B}[0;0m
+        Second diagnostic explanation
+        --> /path/to/file.md:12:1-12:10
+
+        \u{001B}[1;33mwarning: Third diagnostic summary\u{001B}[0;0m
+        Third diagnostic explanation
+        --> /path/to/other/file.md
+        """)
+    }
+
+    func testDisplaysSource() {
+        let identifier = "org.swift.docc.test-identifier"
+        let summary = "Test diagnostic summary"
+        let explanation = "Test diagnostic explanation."
+        let baseURL =  Bundle.module.url(
+            forResource: "TestBundle", withExtension: "docc", subdirectory: "Test Bundles")!
+        let source = baseURL.appendingPathComponent("TestTutorial.tutorial")
+        let range = SourceLocation(line: 44, column: 59, source: source)..<SourceLocation(line: 44, column: 138, source: source)
+
+        let logger = Logger()
+        let consumer = DiagnosticConsoleWriter(logger, baseURL: baseURL, highlight: true)
+
+        let diagnostic = Diagnostic(source: source, severity: .warning, range: range, identifier: identifier, summary: summary, explanation: explanation)
+        let problem = Problem(diagnostic: diagnostic, possibleSolutions: [])
+        consumer.receive([problem])
+        try? consumer.finalize()
+        print(logger.output)
+        XCTAssertEqual(logger.output, """
+        \u{001B}[1;33mwarning: \(summary)\u{001B}[0;0m
+        \(explanation)
+          --> TestTutorial.tutorial:44:59-44:138
+        42 |          ut labore et dolore magna aliqua. Phasellus faucibus scelerisque eleifend donec pretium. 
+        43 |          Ultrices dui sapien eget mi proin sed libero enim. Quis auctor elit sed vulputate mi sit amet.
+        44 +          This section link refers to this section itself: \u{001B}[1;32m<doc:/tutorials/Test-Bundle/TestTutorial#Create-a-New-AR-Project-%F0%9F%92%BB>.\u{001B}[0;0m
+        45 |          This is an external link to Swift documentation: [Swift Documentation](https://swift.org/documentation/).
+        46 |          This section link refers to the next section in this file: <doc:/tutorials/Test-Bundle/TestTutorial#Initiate-ARKit-Plane-Detection>.
+        """)
+    }
+
+    func testDisplaysPossibleSolutionsSummary() {
+        let identifier = "org.swift.docc.test-identifier"
+        let summary = "Test diagnostic summary"
+        let explanation = "Test diagnostic explanation."
+        let baseURL =  Bundle.module.url(
+            forResource: "TestBundle", withExtension: "docc", subdirectory: "Test Bundles")!
+        let source = baseURL.appendingPathComponent("TestTutorial.tutorial")
+        let diagnosticRange = SourceLocation(line: 44, column: 59, source: source)..<SourceLocation(line: 44, column: 138, source: source)
+        let diagnostic = Diagnostic(source: source, severity: .warning, range: diagnosticRange, identifier: identifier, summary: summary, explanation: explanation)
+
+        do { // Displays solutions with single replacement at the replacement's source.
+            let logger = Logger()
+            let consumer = DiagnosticConsoleWriter(logger, baseURL: baseURL, highlight: true)
+
+            let solutionRange = SourceLocation(line: 44, column: 59, source: source)..<SourceLocation(line: 44, column: 60, source: source)
+            let solution = Solution(
+                summary: "Solution summary",
+                replacements: [.init(range: solutionRange, replacement: "replacement")]
+            )
+
+            let otherSolutionRange = SourceLocation(line: 44, column: 62, source: source)..<SourceLocation(line: 44, column: 64, source: source)
+            let otherSolution = Solution(
+                summary: "Other solution summary",
+                replacements: [.init(range: otherSolutionRange, replacement: "replacement")]
+            )
+
+            let problem = Problem(diagnostic: diagnostic, possibleSolutions: [solution, otherSolution])
+            consumer.receive([problem])
+            try? consumer.finalize()
+
+            print(logger.output)
+            XCTAssertEqual(logger.output, """
+            \u{001B}[1;33mwarning: \(summary)\u{001B}[0;0m
+            \(explanation)
+              --> TestTutorial.tutorial:44:59-44:138
+            42 |          ut labore et dolore magna aliqua. Phasellus faucibus scelerisque eleifend donec pretium. 
+            43 |          Ultrices dui sapien eget mi proin sed libero enim. Quis auctor elit sed vulputate mi sit amet.
+            44 +          This section link refers to this section itself: \u{001B}[1;32m<doc:/tutorials/Test-Bundle/TestTutorial#Create-a-New-AR-Project-%F0%9F%92%BB>.\u{001B}[0;0m
+               |                                                           │  ╰─\u{001B}[1;39msuggestion: Other solution summary\u{001B}[0;0m
+               |                                                           ╰─\u{001B}[1;39msuggestion: Solution summary\u{001B}[0;0m
+            45 |          This is an external link to Swift documentation: [Swift Documentation](https://swift.org/documentation/).
+            46 |          This section link refers to the next section in this file: <doc:/tutorials/Test-Bundle/TestTutorial#Initiate-ARKit-Plane-Detection>.
+            """)
+        }
+
+        do { // Displays solution without replacement at the beginning of the diagnostic range.
+            let logger = Logger()
+            let consumer = DiagnosticConsoleWriter(logger, baseURL: baseURL, highlight: true)
+
+            let solution = Solution(summary: "Solution summary", replacements: [])
+
+            let problem = Problem(diagnostic: diagnostic, possibleSolutions: [solution])
+            consumer.receive([problem])
+            try? consumer.finalize()
+
+            print(logger.output)
+            XCTAssertEqual(logger.output, """
+            \u{001B}[1;33mwarning: \(summary)\u{001B}[0;0m
+            \(explanation)
+              --> TestTutorial.tutorial:44:59-44:138
+            42 |          ut labore et dolore magna aliqua. Phasellus faucibus scelerisque eleifend donec pretium. 
+            43 |          Ultrices dui sapien eget mi proin sed libero enim. Quis auctor elit sed vulputate mi sit amet.
+            44 +          This section link refers to this section itself: \u{001B}[1;32m<doc:/tutorials/Test-Bundle/TestTutorial#Create-a-New-AR-Project-%F0%9F%92%BB>.\u{001B}[0;0m
+               |                                                           ╰─\u{001B}[1;39msuggestion: Solution summary\u{001B}[0;0m
+            45 |          This is an external link to Swift documentation: [Swift Documentation](https://swift.org/documentation/).
+            46 |          This section link refers to the next section in this file: <doc:/tutorials/Test-Bundle/TestTutorial#Initiate-ARKit-Plane-Detection>.
+            """)
+        }
+
+        do { // Displays solution with many replacements at the beginning of the diagnostic range.
+            let logger = Logger()
+            let consumer = DiagnosticConsoleWriter(logger, baseURL: baseURL, highlight: true)
+
+            let firstReplacement = Replacement(
+                range: SourceLocation(line: 44, column: 60, source: source)..<SourceLocation(line: 44, column: 64, source: source),
+                replacement: "first replacement"
+            )
+            let secondReplacement = Replacement(
+                range: SourceLocation(line: 44, column: 68, source: source)..<SourceLocation(line: 44, column: 70, source: source),
+                replacement: "second replacement"
+            )
+            let solution = Solution(summary: "Solution summary", replacements: [firstReplacement, secondReplacement])
+
+            let problem = Problem(diagnostic: diagnostic, possibleSolutions: [solution])
+            consumer.receive([problem])
+            try? consumer.finalize()
+
+            print(logger.output)
+            XCTAssertEqual(logger.output, """
+            \u{001B}[1;33mwarning: \(summary)\u{001B}[0;0m
+            \(explanation)
+              --> TestTutorial.tutorial:44:59-44:138
+            42 |          ut labore et dolore magna aliqua. Phasellus faucibus scelerisque eleifend donec pretium. 
+            43 |          Ultrices dui sapien eget mi proin sed libero enim. Quis auctor elit sed vulputate mi sit amet.
+            44 +          This section link refers to this section itself: \u{001B}[1;32m<doc:/tutorials/Test-Bundle/TestTutorial#Create-a-New-AR-Project-%F0%9F%92%BB>.\u{001B}[0;0m
+               |                                                           ╰─\u{001B}[1;39msuggestion: Solution summary\u{001B}[0;0m
+            45 |          This is an external link to Swift documentation: [Swift Documentation](https://swift.org/documentation/).
+            46 |          This section link refers to the next section in this file: <doc:/tutorials/Test-Bundle/TestTutorial#Initiate-ARKit-Plane-Detection>.
+            """)
+        }
+    }
+}
diff --git a/Tests/SwiftDocCTests/Diagnostics/DiagnosticConsoleWriterTests.swift b/Tests/SwiftDocCTests/Diagnostics/DiagnosticConsoleWriterTests.swift
index d488431359..cc89e85bae 100644
--- a/Tests/SwiftDocCTests/Diagnostics/DiagnosticConsoleWriterTests.swift
+++ b/Tests/SwiftDocCTests/Diagnostics/DiagnosticConsoleWriterTests.swift
@@ -37,7 +37,7 @@ class DiagnosticConsoleWriterTests: XCTestCase {
         let problem = Problem(diagnostic: Diagnostic(source: nil, severity: .warning, range: nil, identifier: "org.swift.docc.tests", summary: "Test diagnostic"), possibleSolutions: [])
 
         let logger = Logger()
-        let consumer = DiagnosticConsoleWriter(logger, formattingOptions: [])
+        let consumer = DiagnosticConsoleWriter(logger, formattingOptions: [.formatConsoleOutputForTools])
         XCTAssert(logger.output.isEmpty)
         consumer.receive([problem])
         XCTAssertEqual(logger.output, "warning: Test diagnostic\n")
@@ -47,7 +47,7 @@ class DiagnosticConsoleWriterTests: XCTestCase {
         let problem = Problem(diagnostic: Diagnostic(source: nil, severity: .warning, range: nil, identifier: "org.swift.docc.tests", summary: "Test diagnostic"), possibleSolutions: [])
 
         let logger = Logger()
-        let consumer = DiagnosticConsoleWriter(logger, formattingOptions: [])
+        let consumer = DiagnosticConsoleWriter(logger, formattingOptions: [.formatConsoleOutputForTools])
         XCTAssert(logger.output.isEmpty)
         consumer.receive([problem, problem])
         XCTAssertEqual(logger.output, """
@@ -127,28 +127,4 @@ class DiagnosticConsoleWriterTests: XCTestCase {
             """)
         }
     }
-    
-    func testDoesNotEmitFixits() {
-        let source = URL(string: "/path/to/file.md")!
-        let range = SourceLocation(line: 1, column: 8, source: source)..<SourceLocation(line: 10, column: 21, source: source)
-        let identifier = "org.swift.docc.test-identifier"
-        let summary = "Test diagnostic summary"
-        let explanation = "Test diagnostic explanation."
-        let expectedLocation = "/path/to/file.md:1:8"
-        
-        let replacementRange = SourceLocation(line: 1, column: 8, source: source)..<SourceLocation(line: 1, column: 24, source: source)
-        let replacement = Replacement(range: replacementRange, replacement: "Replacement text")
-        let solution = Solution(summary: "", replacements: [replacement])
-        let diagnostic = Diagnostic(source: source, severity: .error, range: range, identifier: identifier, summary: summary, explanation: explanation)
-        let problem = Problem(diagnostic: diagnostic, possibleSolutions: [solution])
-        
-        let logger = Logger()
-        let consumer = DiagnosticConsoleWriter(logger, formattingOptions: [])
-        consumer.receive([problem])
-        XCTAssertEqual(logger.output, """
-            \(expectedLocation): error: \(summary)
-            \(explanation)
-            
-            """)
-    }
 }
diff --git a/Tests/SwiftDocCTests/Diagnostics/DiagnosticEngineTests.swift b/Tests/SwiftDocCTests/Diagnostics/DiagnosticEngineTests.swift
index df23ce0054..efeed413d8 100644
--- a/Tests/SwiftDocCTests/Diagnostics/DiagnosticEngineTests.swift
+++ b/Tests/SwiftDocCTests/Diagnostics/DiagnosticEngineTests.swift
@@ -114,7 +114,7 @@ class DiagnosticEngineTests: XCTestCase {
         defaultEngine.emit(warning)
         defaultEngine.emit(information)
         defaultEngine.emit(hint)
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: defaultEngine.problems), """
+        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: defaultEngine.problems, options: .formatConsoleOutputForTools), """
             error: Test error
             warning: Test warning
             """)
@@ -124,7 +124,7 @@ class DiagnosticEngineTests: XCTestCase {
         engine.emit(warning)
         engine.emit(information)
         engine.emit(hint)
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: engine.problems), """
+        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: engine.problems, options: .formatConsoleOutputForTools), """
             error: Test error
             warning: Test warning
             note: Test information
@@ -140,7 +140,7 @@ class DiagnosticEngineTests: XCTestCase {
         defaultEngine.emit(error)
         defaultEngine.emit(warning)
         defaultEngine.emit(information)
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: defaultEngine.problems), """
+        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: defaultEngine.problems, options: .formatConsoleOutputForTools), """
             error: Test error
             warning: Test warning
             """)
@@ -149,7 +149,7 @@ class DiagnosticEngineTests: XCTestCase {
         engine.emit(error)
         engine.emit(warning)
         engine.emit(information)
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: engine.problems), """
+        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: engine.problems, options: .formatConsoleOutputForTools), """
             error: Test error
             error: Test warning
             note: Test information
@@ -159,7 +159,7 @@ class DiagnosticEngineTests: XCTestCase {
         errorFilterLevelEngine.emit(error)
         errorFilterLevelEngine.emit(warning)
         errorFilterLevelEngine.emit(information)
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: errorFilterLevelEngine.problems), """
+        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: errorFilterLevelEngine.problems, options: .formatConsoleOutputForTools), """
             error: Test error
             error: Test warning
             """)
diff --git a/Tests/SwiftDocCTests/Diagnostics/DiagnosticTests.swift b/Tests/SwiftDocCTests/Diagnostics/DiagnosticTests.swift
index 750e961d55..4a9370bceb 100644
--- a/Tests/SwiftDocCTests/Diagnostics/DiagnosticTests.swift
+++ b/Tests/SwiftDocCTests/Diagnostics/DiagnosticTests.swift
@@ -66,7 +66,7 @@ class DiagnosticTests: XCTestCase {
         let range = SourceLocation(line: 1, column: 1, source: URL(fileURLWithPath: path))..<SourceLocation(line: 2, column: 2, source: URL(fileURLWithPath: path))
         let diagnostic = Diagnostic(source: URL(fileURLWithPath: path), severity: .error, range: range, identifier: "org.swift.docc.test.Diagnostic.localizedDescription", summary: "This is a test diagnostic")
         let expectedDescription = "\(path):1:1: error: This is a test diagnostic"
-        XCTAssertEqual(expectedDescription, DiagnosticConsoleWriter.formattedDescription(for: diagnostic))
+        XCTAssertEqual(expectedDescription, DiagnosticConsoleWriter.formattedDescription(for: diagnostic, options: .formatConsoleOutputForTools))
     }
     
     /// Test that the file path is printed even when range is nil, indicating a whole-file diagnostic or a diagnostic where the range is unknown.
@@ -74,7 +74,7 @@ class DiagnosticTests: XCTestCase {
         let path = "/tmp/foo.md"
         let diagnostic = Diagnostic(source: URL(fileURLWithPath: path), severity: .error, range: nil, identifier: "org.swift.docc.test.Diagnostic.localizedDescription", summary: "This is a test diagnostic")
         let expectedDescription = "\(path): error: This is a test diagnostic"
-        XCTAssertEqual(expectedDescription, DiagnosticConsoleWriter.formattedDescription(for: diagnostic))
+        XCTAssertEqual(expectedDescription, DiagnosticConsoleWriter.formattedDescription(for: diagnostic, options: .formatConsoleOutputForTools))
     }
     
     /// Test offsetting diagnostic ranges
@@ -107,16 +107,16 @@ class DiagnosticTests: XCTestCase {
         let expectedLocation = "/path/to/file.md:1:8"
 
         let error = Diagnostic(source: source, severity: .error, range: range, identifier: identifier, summary: summary, explanation: explanation)
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: error), "\(expectedLocation): error: \(summary)\n\(explanation)")
+        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: error, options: .formatConsoleOutputForTools), "\(expectedLocation): error: \(summary)\n\(explanation)")
 
         let warning = Diagnostic(source: source, severity: .warning, range: range, identifier: identifier, summary: summary, explanation: explanation)
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: warning), "\(expectedLocation): warning: \(summary)\n\(explanation)")
+        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: warning, options: .formatConsoleOutputForTools), "\(expectedLocation): warning: \(summary)\n\(explanation)")
 
         let note = Diagnostic(source: source, severity: .information, range: range, identifier: identifier, summary: summary, explanation: explanation)
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: note), "\(expectedLocation): note: \(summary)\n\(explanation)")
+        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: note, options: .formatConsoleOutputForTools), "\(expectedLocation): note: \(summary)\n\(explanation)")
 
         let notice = Diagnostic(source: source, severity: .hint, range: range, identifier: identifier, summary: summary, explanation: explanation)
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: notice), "\(expectedLocation): notice: \(summary)\n\(explanation)")
+        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: notice, options: .formatConsoleOutputForTools), "\(expectedLocation): notice: \(summary)\n\(explanation)")
     }
 
     func testLocalizedDescriptionWithNote() {
@@ -137,7 +137,7 @@ class DiagnosticTests: XCTestCase {
         let expectedNoteLocation = "/a/file/path.md:1:1"
 
         let diagnostic = Diagnostic(source: source, severity: .error, range: range, identifier: identifier, summary: summary, explanation: explanation, notes: [note])
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: diagnostic), """
+        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: diagnostic, options: .formatConsoleOutputForTools), """
         \(expectedLocation): error: \(summary)
         \(explanation)
         \(expectedNoteLocation): note: The message of the note.
diff --git a/Tests/SwiftDocCTests/Diagnostics/ProblemTests.swift b/Tests/SwiftDocCTests/Diagnostics/ProblemTests.swift
index 5e7ab4dbaa..a577690a66 100644
--- a/Tests/SwiftDocCTests/Diagnostics/ProblemTests.swift
+++ b/Tests/SwiftDocCTests/Diagnostics/ProblemTests.swift
@@ -20,18 +20,21 @@ class ProblemTests: XCTestCase {
         let range = SourceLocation(line: 1, column: 8, source: source)..<SourceLocation(line: 10, column: 21, source: source)
         let identifier = "org.swift.docc.test-identifier"
         let summary = "Test diagnostic summary"
+        let solutionSummary = "Test solution summary"
         let explanation = "Test diagnostic explanation."
         let expectedLocation = "/path/to/file.md:1:8"
+        let expectedFixit = "/path/to/file.md:1:8-1:24: fixit: Replacement text"
 
         let replacementRange = SourceLocation(line: 1, column: 8, source: source)..<SourceLocation(line: 1, column: 24, source: source)
         let replacement = Replacement(range: replacementRange, replacement: "Replacement text")
-        let solution = Solution(summary: "", replacements: [replacement])
+        let solution = Solution(summary: solutionSummary, replacements: [replacement])
         let diagnostic = Diagnostic(source: source, severity: .error, range: range, identifier: identifier, summary: summary, explanation: explanation)
         let problem = Problem(diagnostic: diagnostic, possibleSolutions: [solution])
 
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: problem), """
-        \(expectedLocation): error: \(summary)
+        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: problem, options: .formatConsoleOutputForTools), """
+        \(expectedLocation): error: \(summary). \(solutionSummary).
         \(explanation)
+        \(expectedFixit)
         """)
     }
 
@@ -55,10 +58,5 @@ class ProblemTests: XCTestCase {
         \(explanation)
         \(source):1:8-1:24: fixit: Replacement text
         """)
-
-        XCTAssertEqual(DiagnosticConsoleWriter.formattedDescription(for: problem), """
-        \(expectedLocation): error: \(summary)
-        \(explanation)
-        """)
     }
 }
diff --git a/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasAtMostOneTests.swift b/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasAtMostOneTests.swift
index 28af8640a4..2c79436f24 100644
--- a/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasAtMostOneTests.swift	
+++ b/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasAtMostOneTests.swift	
@@ -76,7 +76,7 @@ class HasAtMostOneTests: XCTestCase {
             XCTAssertEqual("""
                  warning: Duplicate 'Child' child directive
                  The 'Parent' directive must have at most one 'Child' child directive
-                 """, DiagnosticConsoleWriter.formattedDescription(for: problems[0].diagnostic))
+                 """, DiagnosticConsoleWriter.formattedDescription(for: problems[0].diagnostic, options: .formatConsoleOutputForTools))
         }
     }
     
diff --git a/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasExactlyOneTests.swift b/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasExactlyOneTests.swift
index 794f0dcbfe..b167bfc73e 100644
--- a/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasExactlyOneTests.swift	
+++ b/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasExactlyOneTests.swift	
@@ -30,7 +30,7 @@ class HasExactlyOneTests: XCTestCase {
             problems.first.map { problem in
                 XCTAssertEqual("org.swift.docc.HasExactlyOne<Parent, TestChild>.Missing", problem.diagnostic.identifier)
                 XCTAssertEqual(
-                    DiagnosticConsoleWriter.formattedDescription(for: problem.diagnostic),
+                    DiagnosticConsoleWriter.formattedDescription(for: problem.diagnostic, options: .formatConsoleOutputForTools),
                     """
                     error: Missing 'Child' child directive
                     The 'Parent' directive must have exactly one 'Child' child directive
@@ -87,7 +87,7 @@ class HasExactlyOneTests: XCTestCase {
             XCTAssertEqual("""
                  error: Duplicate 'Child' child directive
                  The 'Parent' directive must have exactly one 'Child' child directive
-                 """, DiagnosticConsoleWriter.formattedDescription(for: problems[0].diagnostic))
+                 """, DiagnosticConsoleWriter.formattedDescription(for: problems[0].diagnostic, options: .formatConsoleOutputForTools))
 
         }
     }
diff --git a/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasOnlyKnownArgumentsTests.swift b/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasOnlyKnownArgumentsTests.swift
index 922b1fc644..de61619e5c 100644
--- a/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasOnlyKnownArgumentsTests.swift	
+++ b/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasOnlyKnownArgumentsTests.swift	
@@ -68,6 +68,6 @@ class HasOnlyKnownArgumentsTests: XCTestCase {
         
         XCTAssertEqual(problems.count, 1)
         guard let first = problems.first else { return }
-        XCTAssertEqual("error: Unknown argument 'baz' in Intro. These arguments are currently unused but allowed: 'bark', 'woof'.", DiagnosticConsoleWriter.formattedDescription(for: first.diagnostic))
+        XCTAssertEqual("error: Unknown argument 'baz' in Intro. These arguments are currently unused but allowed: 'bark', 'woof'.", DiagnosticConsoleWriter.formattedDescription(for: first.diagnostic, options: .formatConsoleOutputForTools))
     }
 }
diff --git a/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasOnlyKnownDirectivesTests.swift b/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasOnlyKnownDirectivesTests.swift
index a3350051b6..e2cdead3ef 100644
--- a/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasOnlyKnownDirectivesTests.swift	
+++ b/Tests/SwiftDocCTests/Semantics/General Purpose Analyses/HasOnlyKnownDirectivesTests.swift	
@@ -121,7 +121,7 @@ class HasOnlyKnownDirectivesTests: XCTestCase {
         
         XCTAssertEqual(problems.count, 1)
         guard let first = problems.first else { return }
-        XCTAssertEqual("error: 'baz' directive is unsupported as a child of the 'dir' directive\nThese directives are allowed: 'Comment', 'bar', 'bark', 'foo', 'woof'", DiagnosticConsoleWriter.formattedDescription(for: first.diagnostic))
+        XCTAssertEqual("error: 'baz' directive is unsupported as a child of the 'dir' directive\nThese directives are allowed: 'Comment', 'bar', 'bark', 'foo', 'woof'", DiagnosticConsoleWriter.formattedDescription(for: first.diagnostic, options: .formatConsoleOutputForTools))
     }
 }