ローカル開発サーバーを調査、管理、終了するためのMCPサーバーです。:3000で何が動いているか推測するのはやめましょう。
terminal-history-mcpと組み合わせることで、AIエージェントがあなたの開発環境（何を実行したか、何が実行中か）を完全に把握できるようになります。
すべての開発者が毎日直面する問題です：
Error: listen EADDRINUSE :::3000 — どのプロセスがポートを占有しているのか？
先週から放置されたままのnode / vite / nextのPIDがメモリを消費している
プロジェクトを切り替えた際、どの開発サーバーが動いたままか分からない
lsof -i :3000、kill -9 <pid>を繰り返す
localhost-mcpを使えば、ツール呼び出し一つで解決します。
Related MCP server: Git Insight MCP
npm install -g localhost-mcpClaude Codeに組み込む：
claude mcp add --scope user localhost -- localhost-mcpまたは、MCP互換クライアントであれば何でも使用可能です。このコマンドはstdio MCPサーバーとして実行されます。
ツール | 目的 |
| ポート、PID、フレームワーク、プロジェクト、稼働時間、メモリ、CPUを含むすべてのリスニング中の開発サーバーを表示 |
| 特定のポートを調査 — 誰が占有しているか |
| PIDまたはポートで終了。デフォルトはドライラン。実行するには |
| 長時間稼働、アイドル状態、メモリ消費の激しい開発サーバーを検出 |
| なぜポートXがビジーなのか + 近隣の空きポート5つを提案 |
{
"port": 3000,
"pid": 48211,
"process": "node",
"cmdline": "next dev",
"cwd": "/Users/me/code/myapp",
"project_name": "myapp",
"framework": "next.js",
"uptime_seconds": 14523,
"memory_mb": 412,
"cpu_pct": 0.3,
"user": "me"
}kill_serverはデフォルトでドライランです。confirm=trueを渡す必要があります。
PID < 1000（システムプロセス）の終了を拒否します。
開発ホワイトリスト（node, python, ruby, go, deno, bun, php, java, rails, vite, nextなど）以外のプロセスの終了を拒否します。
まずSIGTERMを送信し、5秒のタイムアウト後にSIGKILLへエスカレーションします。
next.js, vite, nuxt, remix, astro, webpack-dev-server, esbuild, create-react-app, express, fastify, koa, hono, rails, django, flask, fastapi, uvicorn, gunicorn, deno, bun, php-builtin, jekyll, hugo.
コマンドラインが汎用的（node server.jsなど）な場合は、package.jsonをスニッフィングしてフォールバックします。
macOS — 完全サポート（lsofを使用）
Linux — 完全サポート（lsof + /procを使用）
Windows — 基本的なポートスキャンのみ（netstatを使用）；カレントディレクトリ / フレームワーク検出は制限あり
localhost-mcp list # JSON list of all dev servers
localhost-mcp zombies # JSON list of zombie candidates
localhost-mcp # Start MCP stdio servergit clone https://github.com/hasanjahidul/localhost-mcp.git
cd localhost-mcp
npm install
npm run build
node dist/cli.js listMIT
Read-only. Flags dev servers that look abandoned — all three of: uptime > 6h AND CPU < 1% AND memory > 100MB. By default it excludes known always-on noise (VS Code server, language servers, other MCP servers, postgres/redis, sidekiq, etc.); set include_excluded: true to also list those. Each candidate comes with the reasons it matched. This tool never kills anything — pass results to kill_server. Returns { count, candidates[] }.
Inputs: include_excluded. Returns: count, candidates
Terminates a local dev server by pid or port. DESTRUCTIVE. Safe by default: with no confirm, this is a DRY RUN — it reports what it would kill and changes nothing. Pass confirm: true to actually terminate: sends SIGTERM, waits up to 5s, then escalates to SIGKILL (or SIGKILL immediately if force: true). Refuses PIDs below 1000 and processes that don't look like dev servers. Provide exactly one of pid or port. Returns what was (or would be) killed and the signal used.
Inputs: pid, port, force, confirm. Returns: pid, port, killed, signal, +3 more
Read-only. Lists every local development server (next, vite, nuxt, remix, astro, rails, django, flask, express, deno, bun, etc.) currently LISTENING on a TCP port. For each: port, pid, process name, command line, working directory, project name, detected framework, uptime, memory (MB), CPU %, and owning user. Uses lsof on macOS/Linux and netstat on Windows; on Windows the cwd/framework fields are limited. Takes no arguments. Returns { count, servers[] }.
Inputs: no named parameters. Returns: count, servers
Read-only. Diagnoses an EADDRINUSE situation: given a port, returns the dev server currently blocking it plus 5 free alternative ports nearby. Use it when a listen EADDRINUSE error fires and you want both the culprit and a port to switch to.
Inputs: port (required). Returns: port, blocked_by, alternatives
Read-only. Inspects a single TCP port and reports the dev server holding it (same fields as list_dev_servers). If nothing is listening, or the listener is not a recognised dev process, returns { port, status: "free" }. Useful for answering "what's on :3000?" before starting or killing something.
Inputs: port (required). Returns: Either a dev-server record (see list_dev_servers) or `{ port, status: "free" }`.
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
Loading tool schema changelog…
Scored across 5 tools
Each tool has a clearly distinct purpose: listing servers, inspecting a single port, finding zombies, killing servers, and diagnosing port conflicts. There is no functional overlap.
Tool names use snake_case, and most follow a verb_noun pattern (find_zombies, kill_server, list_dev_servers). However, port_conflict and port_info are noun-first, which is a minor inconsistency.
With 5 tools, the set is well-scoped for managing local dev servers: query, inspect, cleanup, and conflict resolution. No tool feels superfluous or missing.
The tools cover listing, inspecting, zombie identification, killing, and conflict diagnosis. There is a minor gap in that bulk operations (e.g., kill all zombies) are not directly supported, but the intended workflow is clear.
2,000+ MCP servers read at source level. Know what one does before you connect. Free, no key.
One MCP server for all your MCP servers: code mode, per-tool permissions, approvals and audit.
Scan any MCP server for tool-poisoning, security, auth & license. Trust score before install.
Self-hosted MCP server: 26 deterministic dev, security, and EVM tools.