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fix: Remove copy/pasta 🍝 in Mcp[Aync]Tool #358

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Merged
copybara-service merged 1 commit into from
Aug 15, 2025
+173 −169
Merged

fix: Remove copy/pasta 🍝 in Mcp[Aync]Tool #358

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161 changes: 161 additions & 0 deletions core/src/main/java/com/google/adk/tools/mcp/AbstractMcpTool.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,161 @@
/*
* Copyright 2025 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package com.google.adk.tools.mcp;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.adk.tools.BaseTool;
import com.google.common.collect.ImmutableMap;
import com.google.genai.types.FunctionDeclaration;
import com.google.genai.types.Schema;
import io.modelcontextprotocol.spec.McpSchema.CallToolResult;
import io.modelcontextprotocol.spec.McpSchema.Content;
import io.modelcontextprotocol.spec.McpSchema.JsonSchema;
import io.modelcontextprotocol.spec.McpSchema.TextContent;
import io.modelcontextprotocol.spec.McpSchema.Tool;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Optional;

/**
* Base class for MCP tools.
*
* @param <T> The type of the MCP session client.
*/
public abstract class AbstractMcpTool<T> extends BaseTool {

protected final Tool mcpTool;
protected final McpSessionManager mcpSessionManager;
protected final ObjectMapper objectMapper;

// Volatile ensures write visibility in the asynchronous chain for McpAsyncTool.
protected volatile T mcpSession;

protected AbstractMcpTool(
Tool mcpTool, T mcpSession, McpSessionManager mcpSessionManager, ObjectMapper objectMapper) {
super(
mcpTool == null ? "" : mcpTool.name(),
mcpTool == null ? "" : (mcpTool.description().isEmpty() ? "" : mcpTool.description()));

if (mcpTool == null) {
throw new IllegalArgumentException("mcpTool cannot be null");
}
if (mcpSession == null) {
throw new IllegalArgumentException("mcpSession cannot be null");
}
if (mcpSessionManager == null) {
throw new IllegalArgumentException("mcpSessionManager cannot be null");
}
if (objectMapper == null) {
throw new IllegalArgumentException("objectMapper cannot be null");
}
this.mcpTool = mcpTool;
this.mcpSession = mcpSession;
this.mcpSessionManager = mcpSessionManager;
this.objectMapper = objectMapper;
}

public T getMcpSession() {
return this.mcpSession;
}

protected Schema toGeminiSchema(JsonSchema openApiSchema) {
try {
return GeminiSchemaUtil.toGeminiSchema(openApiSchema, this.objectMapper);
} catch (IOException | IllegalArgumentException e) {
throw new IllegalArgumentException(
"Error generating function declaration for tool '" + this.name() + "': " + e.getMessage(),
e);
}
}

@Override
public Optional<FunctionDeclaration> declaration() {
try {
Schema schema = toGeminiSchema(this.mcpTool.inputSchema());
return Optional.ofNullable(schema)
.map(
value ->
FunctionDeclaration.builder()
.name(this.name())
.description(this.description())
.parameters(value)
.build());
} catch (IllegalArgumentException e) {
System.err.println(e.getMessage());
return Optional.empty();
}
}

@SuppressWarnings("PreferredInterfaceType") // BaseTool.runAsync() returns Map<String, Object>
protected static Map<String, Object> wrapCallResult(
ObjectMapper objectMapper, String mcpToolName, CallToolResult callResult) {
if (callResult == null) {
return ImmutableMap.of("error", "MCP framework error: CallToolResult was null");
}

List<Content> contents = callResult.content();
Boolean isToolError = callResult.isError();

if (isToolError != null && isToolError) {
String errorMessage = "Tool execution failed.";
if (contents != null
&& !contents.isEmpty()
&& contents.get(0) instanceof TextContent textContent) {
if (textContent.text() != null && !textContent.text().isEmpty()) {
errorMessage += " Details: " + textContent.text();
}
}
return ImmutableMap.of("error", errorMessage);
}

if (contents == null || contents.isEmpty()) {
return ImmutableMap.of();
}

List<String> textOutputs = new ArrayList<>();
for (Content content : contents) {
if (content instanceof TextContent textContent) {
if (textContent.text() != null) {
textOutputs.add(textContent.text());
}
}
}

if (textOutputs.isEmpty()) {
return ImmutableMap.of(
"error",
"Tool '" + mcpToolName + "' returned content that is not TextContent.",
"content_details",
contents.toString());
}

List<Map<String, Object>> resultMaps = new ArrayList<>();
for (String textOutput : textOutputs) {
try {
resultMaps.add(
objectMapper.readValue(textOutput, new TypeReference<Map<String, Object>>() {}));
} catch (JsonProcessingException e) {
resultMaps.add(ImmutableMap.of("text", textOutput));
}
}
return ImmutableMap.of("text_output", resultMaps);
}
}
57 changes: 5 additions & 52 deletions core/src/main/java/com/google/adk/tools/mcp/McpAsyncTool.java
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Original file line number Diff line number Diff line change
Expand Up @@ -20,20 +20,15 @@

import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.adk.JsonBaseModel;
import com.google.adk.tools.BaseTool;
import com.google.adk.tools.ToolContext;
import com.google.common.collect.ImmutableMap;
import com.google.genai.types.FunctionDeclaration;
import com.google.genai.types.Schema;
import io.modelcontextprotocol.client.McpAsyncClient;
import io.modelcontextprotocol.spec.McpSchema;
import io.modelcontextprotocol.spec.McpSchema.CallToolRequest;
import io.modelcontextprotocol.spec.McpSchema.JsonSchema;
import io.modelcontextprotocol.spec.McpSchema.Tool;
import io.reactivex.rxjava3.core.Maybe;
import io.reactivex.rxjava3.core.Single;
import java.util.Map;
import java.util.Optional;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

Expand All @@ -45,16 +40,10 @@
* <p>This wraps a MCP Tool interface and an active MCP Session. It invokes the MCP Tool through
* executing the tool from remote MCP Session.
*/
public final class McpAsyncTool extends BaseTool {
public final class McpAsyncTool extends AbstractMcpTool<McpAsyncClient> {

private static final Logger logger = LoggerFactory.getLogger(McpAsyncTool.class);

Tool mcpTool;
// Volatile ensures write visibility in the asynchronous chain.
volatile McpAsyncClient mcpSession;
McpSessionManager mcpSessionManager;
ObjectMapper objectMapper;

/**
* Creates a new McpAsyncTool with the default ObjectMapper.
*
Expand All @@ -65,7 +54,7 @@ public final class McpAsyncTool extends BaseTool {
*/
public McpAsyncTool(
Tool mcpTool, McpAsyncClient mcpSession, McpSessionManager mcpSessionManager) {
this(mcpTool, mcpSession, mcpSessionManager, JsonBaseModel.getMapper());
super(mcpTool, mcpSession, mcpSessionManager, JsonBaseModel.getMapper());
}

/**
Expand All @@ -82,31 +71,7 @@ public McpAsyncTool(
McpAsyncClient mcpSession,
McpSessionManager mcpSessionManager,
ObjectMapper objectMapper) {
super(
mcpTool == null ? "" : mcpTool.name(),
mcpTool == null ? "" : (mcpTool.description().isEmpty() ? "" : mcpTool.description()));

if (mcpTool == null) {
throw new IllegalArgumentException("mcpTool cannot be null");
}
if (mcpSession == null) {
throw new IllegalArgumentException("mcpSession cannot be null");
}
if (objectMapper == null) {
throw new IllegalArgumentException("objectMapper cannot be null");
}
this.mcpTool = mcpTool;
this.mcpSession = mcpSession;
this.mcpSessionManager = mcpSessionManager;
this.objectMapper = objectMapper;
}

public McpAsyncClient getMcpSession() {
return this.mcpSession;
}

public Schema toGeminiSchema(JsonSchema openApiSchema) {
return Schema.fromJson(objectMapper.valueToTree(openApiSchema).toString());
super(mcpTool, mcpSession, mcpSessionManager, objectMapper);
}

private Single<McpSchema.InitializeResult> reintializeSession() {
Expand All @@ -129,16 +94,6 @@ private Single<McpSchema.InitializeResult> reintializeSession() {
.toFuture());
}

@Override
public Optional<FunctionDeclaration> declaration() {
return Optional.of(
FunctionDeclaration.builder()
.name(this.name())
.description(this.description())
.parameters(toGeminiSchema(this.mcpTool.inputSchema()))
.build());
}

@Override
public Single<Map<String, Object>> runAsync(Map<String, Object> args, ToolContext toolContext) {
return Single.defer(
Expand All @@ -147,12 +102,10 @@ public Single<Map<String, Object>> runAsync(Map<String, Object> args, ToolContex
this.mcpSession
.callTool(new CallToolRequest(this.name(), ImmutableMap.copyOf(args)))
.toFuture())
.map(
callResult ->
McpTool.wrapCallResult(this.objectMapper, this.name(), callResult))
.map(callResult -> wrapCallResult(this.objectMapper, this.name(), callResult))
.switchIfEmpty(
Single.fromCallable(
() -> McpTool.wrapCallResult(this.objectMapper, this.name(), null))))
() -> wrapCallResult(this.objectMapper, this.name(), null))))
.retryWhen(
errors ->
errors
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