core[minor]: Standardize tool choice

langchain-core/src/language_models/chat_models.ts

@@ -46,6 +46,9 @@ import { concat } from "../utils/stream.js";
 import { RunnablePassthrough } from "../runnables/passthrough.js";
 import { isZodSchema } from "../utils/types/is_zod_schema.js";
 
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+type ToolChoice = string | Record<string, any> | "auto" | "any";
+
 /**
  * Represents a serialized chat model.
  */
@@ -73,7 +76,23 @@ export type BaseChatModelParams = BaseLanguageModelParams;
 /**
  * Represents the call options for a base chat model.
  */
-export type BaseChatModelCallOptions = BaseLanguageModelCallOptions;
+export type BaseChatModelCallOptions = BaseLanguageModelCallOptions & {
+  /**
+   * Specifies how the chat model should use tools.
+   * @default undefined
+   *
+   * Possible values:
+   * - "auto": The model may choose to use any of the provided tools, or none.
+   * - "any": The model must use one of the provided tools.
+   * - "none": The model must not use any tools.
+   * - A string (not "auto", "any", or "none"): The name of a specific tool the model must use.
+   * - An object: A custom schema specifying tool choice parameters. Specific to the provider.
+   *
+   * Note: Not all providers support tool_choice. An error will be thrown
+   * if used with an unsupporting model.
+   */
+  tool_choice?: ToolChoice;
+};
 
 /**
  * Creates a transform stream for encoding chat message chunks.

libs/langchain-anthropic/src/chat_models.ts

@@ -21,12 +21,12 @@ import {
 import { getEnvironmentVariable } from "@langchain/core/utils/env";
 import {
   BaseChatModel,
+  BaseChatModelCallOptions,
   LangSmithParams,
   type BaseChatModelParams,
 } from "@langchain/core/language_models/chat_models";
 import {
   type StructuredOutputMethodOptions,
-  type BaseLanguageModelCallOptions,
   type BaseLanguageModelInput,
   type ToolDefinition,
   isOpenAITool,
@@ -53,30 +53,23 @@ import {
   extractToolCalls,
 } from "./output_parsers.js";
 import { AnthropicToolResponse } from "./types.js";
+import {
+  AnthropicToolChoice,
+  AnthropicToolTypes,
+  handleToolChoice,
+} from "./utils.js";
 
 type AnthropicMessage = Anthropic.MessageParam;
 type AnthropicMessageCreateParams = Anthropic.MessageCreateParamsNonStreaming;
 type AnthropicStreamingMessageCreateParams =
   Anthropic.MessageCreateParamsStreaming;
 type AnthropicMessageStreamEvent = Anthropic.MessageStreamEvent;
 type AnthropicRequestOptions = Anthropic.RequestOptions;
-type AnthropicToolChoice =
-  | {
-      type: "tool";
-      name: string;
-    }
-  | "any"
-  | "auto";
+
 export interface ChatAnthropicCallOptions
-  extends BaseLanguageModelCallOptions,
+  extends BaseChatModelCallOptions,
     Pick<AnthropicInput, "streamUsage"> {
-  tools?: (
-    | StructuredToolInterface
-    | AnthropicTool
-    | Record<string, unknown>
-    | ToolDefinition
-    | RunnableToolLike
-  )[];
+  tools?: AnthropicToolTypes[];
   /**
    * Whether or not to specify what tool the model should use
    * @default "auto"
@@ -855,24 +848,11 @@ export class ChatAnthropicMessages<
     "messages"
   > &
     Kwargs {
-    let tool_choice:
+    const tool_choice:
       | MessageCreateParams.ToolChoiceAuto
       | MessageCreateParams.ToolChoiceAny
       | MessageCreateParams.ToolChoiceTool
-      | undefined;
-    if (options?.tool_choice) {
-      if (options?.tool_choice === "any") {
-        tool_choice = {
-          type: "any",
-        };
-      } else if (options?.tool_choice === "auto") {
-        tool_choice = {
-          type: "auto",
-        };
-      } else {
-        tool_choice = options?.tool_choice;
-      }
-    }
+      | undefined = handleToolChoice(options?.tool_choice);
 
     return {
       model: this.model,

libs/langchain-anthropic/src/utils.ts

@@ -0,0 +1,51 @@
+import type {
+  MessageCreateParams,
+  Tool as AnthropicTool,
+} from "@anthropic-ai/sdk/resources/index.mjs";
+import { ToolDefinition } from "@langchain/core/language_models/base";
+import { RunnableToolLike } from "@langchain/core/runnables";
+import { StructuredToolInterface } from "@langchain/core/tools";
+
+export type AnthropicToolChoice =
+  | {
+      type: "tool";
+      name: string;
+    }
+  | "any"
+  | "auto"
+  | "none"
+  | string;
+
+export type AnthropicToolTypes =
+  | StructuredToolInterface
+  | AnthropicTool
+  | Record<string, unknown>
+  | ToolDefinition
+  | RunnableToolLike;
+
+export function handleToolChoice(
+  toolChoice?: AnthropicToolChoice
+):
+  | MessageCreateParams.ToolChoiceAuto
+  | MessageCreateParams.ToolChoiceAny
+  | MessageCreateParams.ToolChoiceTool
+  | undefined {
+  if (!toolChoice) {
+    return undefined;
+  } else if (toolChoice === "any") {
+    return {
+      type: "any",
+    };
+  } else if (toolChoice === "auto") {
+    return {
+      type: "auto",
+    };
+  } else if (typeof toolChoice === "string") {
+    return {
+      type: "tool",
+      name: toolChoice,
+    };
+  } else {
+    return toolChoice;
+  }
+}

libs/langchain-aws/src/chat_models.ts

@@ -2,14 +2,14 @@ import type { BaseMessage } from "@langchain/core/messages";
 import { AIMessageChunk } from "@langchain/core/messages";
 import type {
   ToolDefinition,
-  BaseLanguageModelCallOptions,
   BaseLanguageModelInput,
 } from "@langchain/core/language_models/base";
 import { CallbackManagerForLLMRun } from "@langchain/core/callbacks/manager";
 import {
   type BaseChatModelParams,
   BaseChatModel,
   LangSmithParams,
+  BaseChatModelCallOptions,
 } from "@langchain/core/language_models/chat_models";
 import type {
   ToolConfiguration,
@@ -30,11 +30,7 @@ import {
 import type { DocumentType as __DocumentType } from "@smithy/types";
 import { StructuredToolInterface } from "@langchain/core/tools";
 import { Runnable, RunnableToolLike } from "@langchain/core/runnables";
-import {
-  BedrockToolChoice,
-  ConverseCommandParams,
-  CredentialType,
-} from "./types.js";
+import { ConverseCommandParams, CredentialType } from "./types.js";
 import {
   convertToConverseTools,
   convertToBedrockToolChoice,
@@ -43,6 +39,7 @@ import {
   handleConverseStreamContentBlockDelta,
   handleConverseStreamMetadata,
   handleConverseStreamContentBlockStart,
+  BedrockConverseToolChoice,
 } from "./common.js";
 
 /**
@@ -127,7 +124,7 @@ export interface ChatBedrockConverseInput
 }
 
 export interface ChatBedrockConverseCallOptions
-  extends BaseLanguageModelCallOptions,
+  extends BaseChatModelCallOptions,
     Pick<
       ChatBedrockConverseInput,
       "additionalModelRequestFields" | "streamUsage"
@@ -149,7 +146,7 @@ export interface ChatBedrockConverseCallOptions
    * or whether to generate text instead.
    * If a tool name is passed, it will force the model to call that specific tool.
    */
-  tool_choice?: "any" | "auto" | string | BedrockToolChoice;
+  tool_choice?: BedrockConverseToolChoice;
 }
 
 /**

libs/langchain-aws/src/common.ts

@@ -258,8 +258,14 @@ export function convertToConverseTools(
   );
 }
 
+export type BedrockConverseToolChoice =
+  | "any"
+  | "auto"
+  | string
+  | BedrockToolChoice;
+
 export function convertToBedrockToolChoice(
-  toolChoice: string | BedrockToolChoice,
+  toolChoice: BedrockConverseToolChoice,
   tools: BedrockTool[]
 ): BedrockToolChoice {
   if (typeof toolChoice === "string") {

libs/langchain-groq/src/chat_models.ts

@@ -69,7 +69,7 @@ import { ToolCallChunk } from "@langchain/core/messages/tool";
 export interface ChatGroqCallOptions extends BaseChatModelCallOptions {
   headers?: Record<string, string>;
   tools?: OpenAIClient.ChatCompletionTool[];
-  tool_choice?: OpenAIClient.ChatCompletionToolChoiceOption;
+  tool_choice?: OpenAIClient.ChatCompletionToolChoiceOption | "any" | string;
   response_format?: { type: "json_object" };
 }
 

libs/langchain-openai/src/chat_models.ts

@@ -64,7 +64,11 @@ import type {
   LegacyOpenAIInput,
 } from "./types.js";
 import { type OpenAIEndpointConfig, getEndpoint } from "./utils/azure.js";
-import { wrapOpenAIClientError } from "./utils/openai.js";
+import {
+  OpenAIToolChoice,
+  formatToOpenAIToolChoice,
+  wrapOpenAIClientError,
+} from "./utils/openai.js";
 import {
   FunctionDef,
   formatFunctionDefinitions,
@@ -274,7 +278,7 @@ export interface ChatOpenAICallOptions
   extends OpenAICallOptions,
     BaseFunctionCallOptions {
   tools?: StructuredToolInterface[] | OpenAIClient.ChatCompletionTool[];
-  tool_choice?: OpenAIClient.ChatCompletionToolChoiceOption;
+  tool_choice?: OpenAIToolChoice;
   promptIndex?: number;
   response_format?: { type: "json_object" };
   seed?: number;
@@ -613,7 +617,7 @@ export class ChatOpenAI<
       tools: isStructuredToolArray(options?.tools)
         ? options?.tools.map(convertToOpenAITool)
         : options?.tools,
-      tool_choice: options?.tool_choice,
+      tool_choice: formatToOpenAIToolChoice(options?.tool_choice),
       response_format: options?.response_format,
       seed: options?.seed,
       ...streamOptionsConfig,

libs/langchain-openai/src/utils/openai.ts

@@ -1,4 +1,8 @@
-import { APIConnectionTimeoutError, APIUserAbortError } from "openai";
+import {
+  APIConnectionTimeoutError,
+  APIUserAbortError,
+  OpenAI as OpenAIClient,
+} from "openai";
 import { zodToJsonSchema } from "zod-to-json-schema";
 import type { StructuredToolInterface } from "@langchain/core/tools";
 import {
@@ -36,3 +40,31 @@ export function formatToOpenAIAssistantTool(tool: StructuredToolInterface) {
     },
   };
 }
+
+export type OpenAIToolChoice =
+  | OpenAIClient.ChatCompletionToolChoiceOption
+  | "any"
+  | string;
+
+export function formatToOpenAIToolChoice(
+  toolChoice?: OpenAIToolChoice
+): OpenAIClient.ChatCompletionToolChoiceOption | undefined {
+  if (!toolChoice) {
+    return undefined;
+  } else if (toolChoice === "any" || toolChoice === "required") {
+    return "required";
+  } else if (toolChoice === "auto") {
+    return "auto";
+  } else if (toolChoice === "none") {
+    return "none";
+  } else if (typeof toolChoice === "string") {
+    return {
+      type: "function",
+      function: {
+        name: toolChoice,
+      },
+    };
+  } else {
+    return toolChoice;
+  }
+}