Execution Tools MCP Server / 执行工具 MCP 服务器

Companion code for AI Agents in Depth, Chapter 4 — Experiment 4-2 ★★. MCP execution tools with LLM approval, auto-verification, and long-output truncation/persist.
配套《深入理解 AI Agent》第 4 章 实验 4-2 ★★。带 LLM 事前审批、自动校验、长输出截断与持久化的执行工具 MCP 服务器。

← Chapter 4 index / 返回第 4 章目录

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English

An MCP (Model Context Protocol) server that provides comprehensive execution tools with built-in safety mechanisms for AI agents.

This project corresponds to Experiment 4-2 in the book’s “Execution Tools” section. It focuses on layered safety (input validation, permission control, LLM pre-approval), automatic syntax verification and feedback loops, and truncation plus persistence of long outputs. Recommended start: python cli.py demo.

Features

Safety Mechanisms

1. LLM-Based Approval: Irreversible operations require approval from a secondary LLM before execution
2. Result Summarization: Execution tool outputs larger than 10,000 characters are automatically summarized by an LLM for easier processing
3. Automatic Verification: Operations that can be verified (e.g., syntax checking) are automatically validated

Tool Categories

File System Tools

• file_write: Write content to files with automatic syntax verification
• file_edit: Edit existing files with diff preview and verification

Generic Execution Tools

• code_interpreter: Execute Python code in a sandboxed environment with result analysis
• virtual_terminal: Execute shell commands with error summarization

External System Integration Tools

• google_calendar_add: Add events to Google Calendar
• github_create_pr: Create GitHub Pull Requests with validation

Installation

# From the repository root: use the shared Chapter 4 environment
uv sync --locked --python 3.12 --extra ch4

# Activate it before changing directories:
# macOS/Linux:
source .venv/bin/activate
# Windows PowerShell: .venv\Scripts\Activate.ps1
# Windows cmd: .venv\Scripts\activate.bat

# pip fallback when uv is not installed:
# python -m pip install -e ".[ch4]"

cd chapter4/execution-tools

# Exact legacy parity path, including optional scientific/ML spreadsheet packages:
# python -m pip install -r requirements.txt

Configuration

1. Copy env.example to .env:

   cp env.example .env
   

2. Configure your environment variables:

   # LLM Configuration (for safety checks and summarization)
   PROVIDER=kimi
   
   # API Keys (set the one for your provider)
   KIMI_API_KEY=your_kimi_key
   # SILICONFLOW_API_KEY=your_siliconflow_key
   # DOUBAO_API_KEY=your_doubao_key
   # OPENROUTER_API_KEY=your_openrouter_key
   
   # Model (optional, defaults to provider's default)
   # MODEL=kimi-k3
   
   # Model parameters
   TEMPERATURE=0.7
   MAX_TOKENS=4096
   
   # External Services (optional)
   GOOGLE_CALENDAR_CREDENTIALS_FILE=credentials.json
   GITHUB_TOKEN=your_github_token
   
   # Safety Settings
   REQUIRE_APPROVAL_FOR_DANGEROUS_OPS=true
   AUTO_SUMMARIZE_COMPLEX_OUTPUT=true
   AUTO_VERIFY_CODE=true
   

Supported Providers: - siliconflow: Qwen/Qwen3-235B-A22B-Thinking-2507 - doubao: doubao-seed-1-6-thinking-250715
- kimi/moonshot: kimi-k3 - openrouter: google/gemini-3.5-flash (or openai/gpt-5.6-luna, anthropic/claude-sonnet-4.6)

Universal OpenRouter fallback: when the configured PROVIDER's key is missing but OPENROUTER_API_KEY is set, the LLM steps (approval, summarization, error/syntax analysis) transparently switch to openrouter via Config.effective_provider(). Set MODEL to a provider/model id for OpenRouter, e.g. MODEL=openai/gpt-5.6-luna.

Usage

CLI entry (cli.py)

cli.py is the unified command-line entry for listing tools, calling each execution tool, and running end-to-end demos. It reuses the same tool implementations as the MCP server, so behavior matches.

# Overview and all subcommands
python cli.py --help

# List all execution tools
python cli.py list

# End-to-end offline demo (recommended first; no API key)
python cli.py demo

# Call a tool individually
python cli.py code --language python --code "print(2 ** 10)"
python cli.py shell "python3 --version"
python cli.py write --path notes.txt --content "hello" --overwrite
python cli.py edit --path notes.txt --search hello --replace world

Global flags (before the subcommand):

Flag	Effect
--provider	Override LLM provider (PROVIDER)
--workspace	Override workspace directory (file ops restricted here)
--no-approval	Disable LLM pre-approval for dangerous ops
--no-verify	Disable auto syntax check for write/code
--no-summarize	Disable LLM summarization of long output (still truncates and persists)

Offline operation: list, demo, and code/shell/write/edit with approval/summarize/non-Python verify off need no API key. API key is needed for: LLM pre-approval, LLM summarization of long output, non-Python syntax checks. calendar and pr also need their external credentials.

Warning — --no-approval: this flag bypasses the LLM pre-approval check for dangerous operations. Use it only in controlled local demos (e.g. a throwaway workspace). Never combine it with real workspaces or destructive commands.

Long-output truncation and persistence: when code_interpreter / virtual_terminal output exceeds the threshold (default 200 lines or 10000 characters), the tool keeps only the first and last 50 lines in context, writes the full output to a temp file, and returns the path in stdout_file / stderr_file. This path does not depend on an LLM and works offline.

Running the MCP Server

python server.py

Using with MCP Client

import asyncio

from mcp import ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client

async def use_tools():
    server_params = StdioServerParameters(
        command="python",
        args=["server.py"],
    )

    async with stdio_client(server_params) as (read, write):
        async with ClientSession(read, write) as session:
            await session.initialize()

            # Use file write tool
            result = await session.call_tool("file_write", {
                "path": "test.py",
                "content": "print('Hello, World!')"
            })

            # Use code interpreter
            result = await session.call_tool("code_interpreter", {
                "code": "import math\nprint(math.sqrt(16))"
            })

            # Use virtual terminal
            result = await session.call_tool("virtual_terminal", {
                "command": "ls -la"
            })


asyncio.run(use_tools())

Testing Individual Tools

# Test file operations
python test_file_tools.py

# Test execution tools
python test_execution_tools.py

# Test external integrations
python test_external_tools.py

Architecture

The server implements a layered architecture:

1. Safety Layer: Intercepts dangerous operations and validates them
2. Tool Layer: Implements individual tool logic
3. Verification Layer: Validates outputs and provides feedback
4. Integration Layer: Connects to external services

Real desktop and Android environments

The exact Experiment 4-2 runner includes two action probes instead of treating installed packages as execution evidence:

• virtual_desktop_execute starts a bounded Xvfb display and headful Chromium, enters an HTTPS URL through xdotool keyboard events, verifies the resulting window title, and hashes a real framebuffer screenshot captured by FFmpeg.
• virtual_mobile_execute connects to a running AndroidWorld Docker emulator, opens Android Wi-Fi Settings through ADB, verifies the focused activity, captures and hashes its pixels, then returns to the launcher with a real input event.

The AndroidWorld image is external and is not vendored. With a populated image available locally, start an API-33 emulator with KVM and run the campaign:

docker run -d --name exp4-2-android --privileged --device /dev/kvm \
  -p 127.0.0.1:5000:5000 android_world_patched:populated3

python run_experiment_4_2.py \
  --android-container exp4-2-android \
  --github-head-branch <pushed-experiment-branch> \
  --github-base-branch <base-branch>

The host desktop path requires Xvfb, xdotool, FFmpeg, and Chromium; the spreadsheet screenshot gate additionally requires LibreOffice Calc. GitHub PR creation queries for an existing head/base PR before mutation, so a campaign retry verifies and reuses the first PR instead of creating a duplicate. External Calendar, GitHub, and email mutations remain credential-gated and are reported as blocked if their real providers are unavailable.

Examples

See examples.py for comprehensive usage examples.

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中文

为 AI Agent 提供带内置安全机制的综合执行工具 MCP（Model Context Protocol）服务器。

本项目对应书中第 4 章「执行工具」一节的实验 4-2，聚焦执行工具的安全机制： 分层安全防护（输入验证、权限控制、LLM 事前审批）、自动语法验证与反馈闭环、 以及长输出的截断与持久化。推荐从 python cli.py demo 开始。

功能

安全机制

1. 基于 LLM 的审批：不可逆操作在执行前需经二级 LLM 审批
2. 结果总结：执行工具输出超过 10,000 字符时由 LLM 自动总结，便于处理
3. 自动校验：可校验的操作（如语法检查）自动验证

工具分类

文件系统工具

• file_write：写入文件，自动语法校验
• file_edit：编辑已有文件，带 diff 预览与校验

通用执行工具

• code_interpreter：沙箱中执行 Python，带结果分析
• virtual_terminal：执行 shell 命令，带错误总结

外部系统集成工具

• google_calendar_add：向 Google Calendar 添加事件
• github_create_pr：创建 GitHub Pull Request（带校验）

安装

# 在仓库根目录使用统一的第 4 章环境
uv sync --locked --python 3.12 --extra ch4

# 切换目录前先激活环境：
# macOS/Linux：
source .venv/bin/activate
# Windows PowerShell：.venv\Scripts\Activate.ps1
# Windows cmd：.venv\Scripts\activate.bat

# 未安装 uv 时可用 pip 兜底：
# python -m pip install -e ".[ch4]"

cd chapter4/execution-tools

# 精确复现旧版单项目环境，含可选科学计算/机器学习/表格处理依赖：
# python -m pip install -r requirements.txt

配置

1. 复制 env.example 为 .env：

   cp env.example .env
   

2. 配置环境变量：

   # LLM Configuration (for safety checks and summarization)
   PROVIDER=kimi
   
   # API Keys (set the one for your provider)
   KIMI_API_KEY=your_kimi_key
   # SILICONFLOW_API_KEY=your_siliconflow_key
   # DOUBAO_API_KEY=your_doubao_key
   # OPENROUTER_API_KEY=your_openrouter_key
   
   # Model (optional, defaults to provider's default)
   # MODEL=kimi-k3
   
   # Model parameters
   TEMPERATURE=0.7
   MAX_TOKENS=4096
   
   # External Services (optional)
   GOOGLE_CALENDAR_CREDENTIALS_FILE=credentials.json
   GITHUB_TOKEN=your_github_token
   
   # Safety Settings
   REQUIRE_APPROVAL_FOR_DANGEROUS_OPS=true
   AUTO_SUMMARIZE_COMPLEX_OUTPUT=true
   AUTO_VERIFY_CODE=true
   

支持的 Provider： - siliconflow：Qwen/Qwen3-235B-A22B-Thinking-2507 - doubao：doubao-seed-1-6-thinking-250715
- kimi/moonshot：kimi-k3 - openrouter：google/gemini-3.5-flash（或 openai/gpt-5.6-luna、anthropic/claude-sonnet-4.6）

OpenRouter 通用兜底：当配置的 PROVIDER 对应 Key 缺失，但设置了 OPENROUTER_API_KEY 时，LLM 步骤（审批、总结、错误/语法分析）经 Config.effective_provider() 透明切换到 openrouter。 为 OpenRouter 设置 MODEL 为 provider/model 形式，例如 MODEL=openai/gpt-5.6-luna。

使用

命令行入口（cli.py）

cli.py 是统一的命令行入口，用于列出、单独调用每个执行工具，并运行端到端演示。 它复用与 MCP 服务器相同的工具实现，因此行为完全一致。

# 查看总帮助与所有子命令
python cli.py --help

# 列出所有执行工具
python cli.py list

# 端到端离线演示（推荐先看这个；无需 API key 即可运行）
python cli.py demo

# 单独调用某个工具
python cli.py code --language python --code "print(2 ** 10)"
python cli.py shell "python3 --version"
python cli.py write --path notes.txt --content "hello" --overwrite
python cli.py edit --path notes.txt --search hello --replace world

全局开关（放在子命令之前）：

开关	作用
--provider	覆盖 LLM 提供商（PROVIDER）
--workspace	覆盖工作目录（文件操作被限制在此目录内）
--no-approval	关闭危险操作的 LLM 事前审批
--no-verify	关闭写文件/代码的自动语法校验
--no-summarize	关闭长输出的 LLM 总结（仍会截断并持久化）

离线运行：list、demo 以及关闭了审批/总结/非 Python 校验的 code/shell/write/edit 均无需 API key。需要 API key 的场景为：LLM 事前审批、 长输出的 LLM 总结、非 Python 语法校验。calendar 与 pr 还额外需要相应外部凭据。

警告 —— --no-approval：该开关会绕过危险操作的 LLM 事前审批，仅适用于受控的本地演示（如一次性临时工作区）。切勿在真实工作区中使用，也不要与破坏性命令搭配使用。

长输出的截断与持久化：当 code_interpreter / virtual_terminal 的输出 超过阈值（默认 200 行或 10000 字符）时，工具只在上下文中保留头尾各 50 行， 完整输出落盘到临时文件，并在返回值的 stdout_file / stderr_file 字段给出路径。 该机制不依赖 LLM，可离线工作。

运行 MCP 服务器

python server.py

配合 MCP 客户端

import asyncio

from mcp import ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client

async def use_tools():
    server_params = StdioServerParameters(
        command="python",
        args=["server.py"],
    )

    async with stdio_client(server_params) as (read, write):
        async with ClientSession(read, write) as session:
            await session.initialize()

            # Use file write tool
            result = await session.call_tool("file_write", {
                "path": "test.py",
                "content": "print('Hello, World!')"
            })

            # Use code interpreter
            result = await session.call_tool("code_interpreter", {
                "code": "import math\nprint(math.sqrt(16))"
            })

            # Use virtual terminal
            result = await session.call_tool("virtual_terminal", {
                "command": "ls -la"
            })


asyncio.run(use_tools())

测试单个工具

# Test file operations
python test_file_tools.py

# Test execution tools
python test_execution_tools.py

# Test external integrations
python test_external_tools.py

架构

服务器采用分层架构：

1. 安全层：拦截危险操作并校验
2. 工具层：实现各工具逻辑
3. 校验层：验证输出并反馈
4. 集成层：对接外部服务

示例

更完整的用法见 examples.py。另见 EXPERIMENT.md 中的实验说明。

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Notes / 说明

• Start with python cli.py demo (no API key).
• 建议从 python cli.py demo 开始（无需 API Key）。
• Long-output truncation/persistence works offline without LLM.
• 长输出截断与持久化不依赖 LLM，可离线。