如何为 Claude 构建本地 MCP Server：文件、命令、截图与应用控制

1mkdir local-mcp-server
2cd local-mcp-server
3uv init --python 3.11
4uv add "mcp[cli]>=1.0,<2.0" "mss>=9.0,<10.0"

1mkdir local-mcp-server
2cd local-mcp-server
3uv init --python 3.11
4uv add "mcp[cli]>=1.0,<2.0" "mss>=9.0,<10.0"

1from __future__ import annotations
2
3import json
4import os
5import platform
6import shlex
7import subprocess
8from pathlib import Path
9from typing import Any
10
11import mss
12from mcp.server.fastmcp import FastMCP
13
14app = FastMCP("local-computer-control", json_response=True)
15
16HOME = Path.home()
17PROJECT_ROOT = Path(__file__).parent.resolve()
18CAPTURE_DIR = PROJECT_ROOT / "captures"
19CAPTURE_DIR.mkdir(exist_ok=True)
20
21ALLOWED_ROOTS = [
22    HOME / "Documents",
23    HOME / "Desktop",
24    PROJECT_ROOT,
25]
26
27ALLOWED_COMMANDS = {
28    "pwd",
29    "ls",
30    "git status",
31    "git diff --stat",
32    "python --version",
33    "node --version",
34    "npm --version",
35}
36
37READABLE_EXTENSIONS = {
38    ".txt",
39    ".md",
40    ".json",
41    ".py",
42    ".js",
43    ".ts",
44    ".tsx",
45    ".jsx",
46    ".yaml",
47    ".yml",
48    ".toml",
49    ".csv",
50    ".log",
51}
52
53def _resolve_path(raw_path: str) -> Path:
54    path = Path(raw_path).expanduser().resolve()
55    for root in ALLOWED_ROOTS:
56        root = root.resolve()
57        if path == root or root in path.parents:
58            return path
59    raise ValueError(f"路径不被允许: {path}")
60
61def _ensure_safe_command(command: str) -> str:
62    normalized = " ".join(shlex.split(command))
63    if normalized not in ALLOWED_COMMANDS:
64        raise ValueError(
65            "命令不被允许。如果确实需要，请将其显式添加到 ALLOWED_COMMANDS 中。"
66        )
67    return normalized
68
69@app.tool()
70def list_files(path: str = "~") -> dict[str, Any]:
71    """列出已批准目录内的文件和文件夹。"""
72    target = _resolve_path(path)
73    if not target.is_dir():
74        raise ValueError(f"不是目录: {target}")
75
76    items = []
77    for child in sorted(target.iterdir(), key=lambda p: (not p.is_dir(), p.name.lower())):
78        items.append(
79            {
80                "name": child.name,
81                "path": str(child),
82                "type": "directory" if child.is_dir() else "file",
83            }
84        )
85
86    return {
87        "path": str(target),
88        "count": len(items),
89        "items": items,
90    }
91
92@app.tool()
93def read_file(path: str, max_chars: int = 12000) -> dict[str, Any]:
94    """从已批准位置读取安全的文本文件。"""
95    target = _resolve_path(path)
96    if not target.is_file():
97        raise ValueError(f"不是文件: {target}")
98    if target.suffix.lower() not in READABLE_EXTENSIONS:
99        raise ValueError(f"不支持的文件类型: {target.suffix}")
100
101    content = target.read_text(encoding="utf-8", errors="replace")
102    truncated = len(content) > max_chars
103    content = content[:max_chars]
104
105    return {
106        "path": str(target),
107        "truncated": truncated,
108        "content": content,
109    }
110
111@app.tool()
112def run_command(command: str, cwd: str | None = None, timeout: int = 15) -> dict[str, Any]:
113    """运行一条白名单中的本地命令。"""
114    safe_command = _ensure_safe_command(command)
115    working_dir = _resolve_path(cwd) if cwd else PROJECT_ROOT
116
117    completed = subprocess.run(
118        safe_command,
119        shell=True,
120        cwd=str(working_dir),
121        capture_output=True,
122        text=True,
123        timeout=timeout,
124    )
125
126    return {
127        "command": safe_command,
128        "cwd": str(working_dir),
129        "returncode": completed.returncode,
130        "stdout": completed.stdout.strip(),
131        "stderr": completed.stderr.strip(),
132    }
133
134@app.tool()
135def take_screenshot(name: str = "latest") -> dict[str, Any]:
136    """截图并保存到本地。"""
137    output_path = CAPTURE_DIR / f"{name}.png"
138
139    with mss.mss() as sct:
140        sct.shot(output=str(output_path))
141
142    return {
143        "saved": True,
144        "path": str(output_path),
145    }
146
147@app.tool()
148def open_target(target: str) -> dict[str, Any]:
149    """使用本地操作系统打开已批准的文件、文件夹、应用或 URL。"""
150    system = platform.system().lower()
151
152    if target.startswith("http://") or target.startswith("https://"):
153        resolved = target
154    else:
155        resolved = str(_resolve_path(target))
156
157    if system == "darwin":
158        subprocess.run(["open", resolved], check=True)
159    elif system == "windows":
160        os.startfile(resolved)  # type: ignore[attr-defined]
161    else:
162        subprocess.run(["xdg-open", resolved], check=True)
163
164    return {
165        "opened": True,
166        "target": resolved,
167    }
168
169if __name__ == "__main__":
170    app.run(transport="stdio")

1{
2  "mcpServers": {
3    "local-computer-control": {
4      "command": "/absolute/path/to/python",
5      "args": [
6        "/absolute/path/to/local-mcp-server/server.py"
7      ]
8    }
9  }
10}

1{
2  "mcpServers": {
3    "local-computer-control": {
4      "command": "/absolute/path/to/uv",
5      "args": [
6        "--directory",
7        "/absolute/path/to/local-mcp-server",
8        "run",
9        "python",
10        "server.py"
11      ]
12    }
13  }
14}

1{
2  "allowed_roots": [
3    "~/Documents",
4    "~/Desktop",
5    "./"
6  ],
7  "allowed_commands": [
8    "pwd",
9    "ls",
10    "git status",
11    "git diff --stat",
12    "python --version"
13  ]
14}