feat(vertex): add native tool calling for Claude models on Vertex AI

hannesrudolph · hannesrudolph · commit 8e2ce92463a4 · 2025-12-18T16:02:23.000-07:00
- Add tool protocol resolution and native tool params to AnthropicVertexHandler
- Handle tool_use blocks and input_json_delta in response streaming
- Add convertOpenAIToolChoice helper method for tool choice conversion
- Add supportsNativeTools and defaultToolProtocol to all Claude models in vertexModels
diff --git a/packages/types/src/providers/vertex.ts b/packages/types/src/providers/vertex.ts
@@ -278,6 +278,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 3.0,
 		outputPrice: 15.0,
 		cacheWritesPrice: 3.75,
@@ -289,6 +291,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 3.0,
 		outputPrice: 15.0,
 		cacheWritesPrice: 3.75,
@@ -300,6 +304,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 1.0,
 		outputPrice: 5.0,
 		cacheWritesPrice: 1.25,
@@ -311,6 +317,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 5.0,
 		outputPrice: 25.0,
 		cacheWritesPrice: 6.25,
@@ -322,6 +330,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 15.0,
 		outputPrice: 75.0,
 		cacheWritesPrice: 18.75,
@@ -333,6 +343,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 15.0,
 		outputPrice: 75.0,
 		cacheWritesPrice: 18.75,
@@ -343,6 +355,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 3.0,
 		outputPrice: 15.0,
 		cacheWritesPrice: 3.75,
@@ -355,6 +369,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 3.0,
 		outputPrice: 15.0,
 		cacheWritesPrice: 3.75,
@@ -365,6 +381,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 3.0,
 		outputPrice: 15.0,
 		cacheWritesPrice: 3.75,
@@ -375,6 +393,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 3.0,
 		outputPrice: 15.0,
 		cacheWritesPrice: 3.75,
@@ -385,6 +405,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: false,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 1.0,
 		outputPrice: 5.0,
 		cacheWritesPrice: 1.25,
@@ -395,6 +417,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 15.0,
 		outputPrice: 75.0,
 		cacheWritesPrice: 18.75,
@@ -405,6 +429,8 @@ export const vertexModels = {
 		contextWindow: 200_000,
 		supportsImages: true,
 		supportsPromptCache: true,
+		supportsNativeTools: true,
+		defaultToolProtocol: "native",
 		inputPrice: 0.25,
 		outputPrice: 1.25,
 		cacheWritesPrice: 0.3,
diff --git a/src/api/providers/anthropic-vertex.ts b/src/api/providers/anthropic-vertex.ts
@@ -1,13 +1,15 @@
 import { Anthropic } from "@anthropic-ai/sdk"
 import { AnthropicVertex } from "@anthropic-ai/vertex-sdk"
 import { GoogleAuth, JWTInput } from "google-auth-library"
+import OpenAI from "openai"
 
 import {
 	type ModelInfo,
 	type VertexModelId,
 	vertexDefaultModelId,
 	vertexModels,
 	ANTHROPIC_DEFAULT_MAX_TOKENS,
+	TOOL_PROTOCOL,
 } from "@roo-code/types"
 
 import { ApiHandlerOptions } from "../../shared/api"
@@ -17,6 +19,8 @@ import { ApiStream } from "../transform/stream"
 import { addCacheBreakpoints } from "../transform/caching/vertex"
 import { getModelParams } from "../transform/model-params"
 import { filterNonAnthropicBlocks } from "../transform/anthropic-filter"
+import { resolveToolProtocol } from "../../utils/resolveToolProtocol"
+import { convertOpenAIToolsToAnthropic } from "../../core/prompts/tools/native-tools/converters"
 
 import { BaseProvider } from "./base-provider"
 import type { SingleCompletionHandler, ApiHandlerCreateMessageMetadata } from "../index"
@@ -63,17 +67,30 @@ export class AnthropicVertexHandler extends BaseProvider implements SingleComple
 		messages: Anthropic.Messages.MessageParam[],
 		metadata?: ApiHandlerCreateMessageMetadata,
 	): ApiStream {
-		let {
-			id,
-			info: { supportsPromptCache },
-			temperature,
-			maxTokens,
-			reasoning: thinking,
-		} = this.getModel()
+		let { id, info, temperature, maxTokens, reasoning: thinking } = this.getModel()
+
+		const { supportsPromptCache } = info
 
 		// Filter out non-Anthropic blocks (reasoning, thoughtSignature, etc.) before sending to the API
 		const sanitizedMessages = filterNonAnthropicBlocks(messages)
 
+		// Enable native tools using resolveToolProtocol (which checks model's defaultToolProtocol)
+		// This matches the approach used in AnthropicHandler
+		// Also exclude tools when tool_choice is "none" since that means "don't use tools"
+		const toolProtocol = resolveToolProtocol(this.options, info, metadata?.toolProtocol)
+		const shouldIncludeNativeTools =
+			metadata?.tools &&
+			metadata.tools.length > 0 &&
+			toolProtocol === TOOL_PROTOCOL.NATIVE &&
+			metadata?.tool_choice !== "none"
+
+		const nativeToolParams = shouldIncludeNativeTools
+			? {
+					tools: convertOpenAIToolsToAnthropic(metadata.tools!),
+					tool_choice: this.convertOpenAIToolChoice(metadata.tool_choice, metadata.parallelToolCalls),
+				}
+			: {}
+
 		/**
 		 * Vertex API has specific limitations for prompt caching:
 		 * 1. Maximum of 4 blocks can have cache_control
@@ -98,6 +115,7 @@ export class AnthropicVertexHandler extends BaseProvider implements SingleComple
 				: systemPrompt,
 			messages: supportsPromptCache ? addCacheBreakpoints(sanitizedMessages) : sanitizedMessages,
 			stream: true,
+			...nativeToolParams,
 		}
 
 		const stream = await this.client.messages.create(params)
@@ -144,6 +162,17 @@ export class AnthropicVertexHandler extends BaseProvider implements SingleComple
 							yield { type: "reasoning", text: (chunk.content_block as any).thinking }
 							break
 						}
+						case "tool_use": {
+							// Emit initial tool call partial with id and name
+							yield {
+								type: "tool_call_partial",
+								index: chunk.index,
+								id: chunk.content_block!.id,
+								name: chunk.content_block!.name,
+								arguments: undefined,
+							}
+							break
+						}
 					}
 
 					break
@@ -158,12 +187,24 @@ export class AnthropicVertexHandler extends BaseProvider implements SingleComple
 							yield { type: "reasoning", text: (chunk.delta as any).thinking }
 							break
 						}
+						case "input_json_delta": {
+							// Emit tool call partial chunks as arguments stream in
+							yield {
+								type: "tool_call_partial",
+								index: chunk.index,
+								id: undefined,
+								name: undefined,
+								arguments: (chunk.delta as any).partial_json,
+							}
+							break
+						}
 					}
 
 					break
 				}
 				case "content_block_stop": {
 					// Block complete - no action needed for now.
+					// NativeToolCallParser handles tool call completion
 					// Note: Signature for multi-turn thinking would require using stream.finalMessage()
 					// after iteration completes, which requires restructuring the streaming approach.
 					break
@@ -227,4 +268,47 @@ export class AnthropicVertexHandler extends BaseProvider implements SingleComple
 			throw error
 		}
 	}
+
+	/**
+	 * Converts OpenAI tool_choice to Anthropic ToolChoice format
+	 * @param toolChoice - OpenAI tool_choice parameter
+	 * @param parallelToolCalls - When true, allows parallel tool calls. When false (default), disables parallel tool calls.
+	 */
+	private convertOpenAIToolChoice(
+		toolChoice: OpenAI.Chat.ChatCompletionCreateParams["tool_choice"],
+		parallelToolCalls?: boolean,
+	): Anthropic.Messages.MessageCreateParams["tool_choice"] | undefined {
+		// Anthropic allows parallel tool calls by default. When parallelToolCalls is false or undefined,
+		// we disable parallel tool use to ensure one tool call at a time.
+		const disableParallelToolUse = !parallelToolCalls
+
+		if (!toolChoice) {
+			// Default to auto with parallel tool use control
+			return { type: "auto", disable_parallel_tool_use: disableParallelToolUse }
+		}
+
+		if (typeof toolChoice === "string") {
+			switch (toolChoice) {
+				case "none":
+					return undefined // Anthropic doesn't have "none", just omit tools
+				case "auto":
+					return { type: "auto", disable_parallel_tool_use: disableParallelToolUse }
+				case "required":
+					return { type: "any", disable_parallel_tool_use: disableParallelToolUse }
+				default:
+					return { type: "auto", disable_parallel_tool_use: disableParallelToolUse }
+			}
+		}
+
+		// Handle object form { type: "function", function: { name: string } }
+		if (typeof toolChoice === "object" && "function" in toolChoice) {
+			return {
+				type: "tool",
+				name: toolChoice.function.name,
+				disable_parallel_tool_use: disableParallelToolUse,
+			}
+		}
+
+		return { type: "auto", disable_parallel_tool_use: disableParallelToolUse }
+	}
 }
