# Lazy MCP Proxy

![Pipeline Status](https://gitlab.com/gitlab-org/ai/lazy-mcp/badges/main/pipeline.svg)

A client-agnostic proxy that converts normal MCP servers to use a lazy-loading pattern, dramatically reducing initial context usage by 90%+ and enabling support for hundreds of commands. It works with **any MCP client** — Claude Desktop, OpenCode, Cursor, VS Code, and more.

## Table of Contents

<!-- TOC_START -->
  - [Table of Contents](#table-of-contents)
  - [Features](#features)
  - [How It Works](#how-it-works)
  - [Installation](#installation)
  - [Usage](#usage)
    - [Streamable HTTP Transport](#streamable-http-transport)
  - [Integration (Claude Desktop, OpenCode, Cursor, VS Code, and more)](#integration-claude-desktop-opencode-cursor-vs-code-and-more)
  - [Example](#example)
  - [Development](#development)
    - [Running from Local Source](#running-from-local-source)
  - [Releases](#releases)
    - [How It Works](#how-it-works)
    - [Required CI/CD Variables](#required-cicd-variables)
      - [`GITLAB_RELEASE_TOKEN`](#gitlabreleasetoken)
      - [`NPM_TOKEN`](#npmtoken)
      - [`PYPI_TOKEN`](#pypitoken)
      - [`CARGO_TOKEN`](#cargotoken)
  - [Configuration Reference](#configuration-reference)
    - [Server Configuration Fields](#server-configuration-fields)
    - [OAuth 2.0 Authentication](#oauth-20-authentication)
    - [Command Format](#command-format)
    - [Environment Variables](#environment-variables)
    - [Transport Configuration](#transport-configuration)
    - [Logging Configuration](#logging-configuration)
    - [Health Monitoring](#health-monitoring)
    - [Config Reload (SIGHUP)](#config-reload-sighup)
  - [Benefits](#benefits)
  - [Documentation](#documentation)
<!-- TOC_END -->

## Features

- **Client-Agnostic**: Works with any MCP client — Claude Desktop, OpenCode, Cursor, VS Code, and any other MCP-compatible tool. Unlike client-specific solutions, lazy-mcp works everywhere you do.
- **Multi-Server Aggregation**: Aggregate multiple MCP servers with on-demand discovery
- **Lazy Loading**: Only discover tools when needed, not upfront
- **Batch Discovery**: Discover multiple servers in one call
- **90%+ Context Reduction**: From ~16K to ~1.5K tokens initially
- **Built-in OAuth 2.0 + PKCE**: Authenticate with OAuth-protected remote servers without a browser — works in sandboxed agent environments
- **Background Health Monitoring**: Probes all servers on startup and periodically; `list_servers` shows accurate health from the first call
- **Hot Config Reload**: Send `SIGHUP` to reload config without restarting — add, remove, or update servers on the fly
- **Streamable HTTP Transport**: Run as an HTTP server — expose lazy-mcp over the network so remote clients can connect via `POST /mcp`

## How It Works

Aggregates multiple MCP servers and exposes four meta-tools:

- `list_servers` - Lists all configured MCP servers with health status. Response includes `pid` and `config_file` so an agent can fix broken config and reload via `kill -HUP <pid>`
- `list_commands` - Discovers tools from specific server(s), supports batch discovery
- `describe_commands` - Gets detailed schemas from a server
- `invoke_command` - Executes commands from a specific server

## Installation

**Homebrew** (macOS and Linux, no runtime dependencies):

```bash
brew tap gitlab-org/lazy-mcp https://gitlab.com/gitlab-org/ai/lazy-mcp
brew install lazy-mcp
```

**Cargo** (if you have Rust installed, no Node.js required):

```bash
cargo install lazy-mcp
```

**If you have Python / uv** (no Node.js required):

```bash
uvx lazy-mcp
```

**If you have Node.js** — use npx to always get the latest version:

```bash
npx lazy-mcp@latest
```

Or install globally (locks to specific version):

```bash
npm install -g lazy-mcp
```

**Docker / Podman**:

```bash
docker build -t lazy-mcp .
docker compose up
```

The image compiles the TypeScript CLI during `docker build`, so this works from a clean checkout without a prebuilt `dist/` directory.

Or with Podman:

```bash
podman build -t lazy-mcp .
podman compose up
```

This runs lazy-mcp in HTTP mode on port 8080 with config mounted from `~/.config/lazy-mcp/servers.json`. See `docker-compose.yml` for configuration options.

## Usage

Create a configuration file at `~/.config/lazy-mcp/servers.json`:

```json
{
  "servers": [
    {
      "name": "chrome-devtools",
      "description": "Chrome DevTools automation",
      "command": ["npx", "-y", "chrome-devtools-mcp@latest"]
    },
    {
      "name": "gitlab",
      "description": "GitLab MCP server",
      "url": "https://gitlab.com/api/v4/mcp"
    },
    {
      "name": "my-remote-server",
      "description": "Custom remote MCP server with static token",
      "url": "https://api.example.com/mcp",
      "headers": {
        "Authorization": "Bearer ${API_TOKEN}"
      }
    },
    {
      "name": "glean",
      "description": "Glean enterprise search (OAuth)",
      "url": "https://your-company.glean.com/mcp/default"
    }
  ]
}
```

Then run:

```bash
# Using npx (recommended - always latest version)
npx lazy-mcp@latest --config ~/.config/lazy-mcp/servers.json

# Or via environment variable
LAZY_MCP_CONFIG=~/.config/lazy-mcp/servers.json npx lazy-mcp@latest

# Or if installed globally
lazy-mcp --config ~/.config/lazy-mcp/servers.json
```

### Streamable HTTP Transport

By default, lazy-mcp communicates over **stdio** (standard MCP transport). You can also run it as an **HTTP server** using the Streamable HTTP transport, allowing remote clients to connect over the network:

**Via config file** — add a `transport` block to `servers.json`:

```json
{
  "servers": [
    { "name": "my-server", "description": "My MCP server", "command": ["python", "server.py"] }
  ],
  "transport": {
    "type": "http",
    "port": 3000,
    "host": "localhost",
    "path": "/mcp",
    "authToken": "${MY_API_KEY}"
  }
}
```

**Via CLI flags** (override config values):

```bash
# Start HTTP server on port 3000
lazy-mcp --config servers.json --transport http --port 3000

# With custom host, path, and auth
lazy-mcp --config servers.json --transport http --port 3000 --host 127.0.0.1 --path /mcp --auth-token "my-secret"
```

**Security note:** `--host 0.0.0.0` exposes the HTTP server on all network interfaces. Use it only inside Docker or trusted networks.

> **Reverse proxy note:** The default Origin check uses the scheme visible to
> lazy-mcp's own socket plus the incoming `Host` header. If you run lazy-mcp
> behind a TLS-terminating reverse proxy, the backend hop is usually plain
> HTTP, so the implicit same-origin shortcut may reject public HTTPS origins.
> In that setup, configure `transport.allowedOrigins` explicitly. If your
> proxy preserves the public `Host` header, configure `transport.allowedHosts`
> too.
>
> Example:
> ```json
> {
>   "transport": {
>     "type": "http",
>     "host": "127.0.0.1",
>     "port": 8080,
>     "path": "/mcp",
>     "allowedHosts": ["mcp.example.com"],
>     "allowedOrigins": ["https://mcp.example.com"]
>   }
> }
> ```
>
> lazy-mcp intentionally does not trust `Forwarded` / `X-Forwarded-*` headers
> by default. If proxy-aware origin reconstruction is ever added, it should be
> behind an explicit trusted-proxy setting.

**Via environment variables** (lowest precedence):

```bash
LAZY_MCP_TRANSPORT=http LAZY_MCP_PORT=3000 LAZY_MCP_AUTH_TOKEN=my-secret lazy-mcp
```

**Precedence**: CLI flags > config file > environment variables > defaults.

Once running, clients connect as a remote MCP server:

```bash
# Quick test with curl
curl -X POST http://localhost:3000/mcp \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -H "Authorization: Bearer ${MY_API_KEY}" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'
```

> **Note**: Server-initiated notifications via GET/SSE are not supported in stateless mode. Use POST for all requests.

## Integration (Claude Desktop, OpenCode, Cursor, VS Code, and more)

Replace multiple MCP server entries with one aggregated proxy:

**Before** (5 separate MCP servers):
```json
{
  "mcp": {
    "chrome-devtools": { "command": ["npx", "lazy-mcp@latest", "npx", "-y", "chrome-devtools-mcp@latest"] },
    "gitlab": { "command": ["npx", "lazy-mcp@latest", "npx", "mcp-remote@latest", "https://..."] },
    "grepai": { "command": ["npx", "lazy-mcp@latest", "grepai", "mcp-serve"] },
    "context7": { "command": ["npx", "-y", "@upstash/context7-mcp"] },
    "perplexity": { "command": ["npx", "-y", "@perplexity-ai/mcp-server"] }
  }
}
```

**After** (Consolidated into 1 multi-server proxy):
```json
{
  "mcp": {
    "lazy-mcp": {
      "type": "local",
      "command": ["npx", "lazy-mcp@latest", "--config", "~/.config/lazy-mcp/servers.json"],
      "enabled": true
    }
  }
}
```

**HTTP mode** — for clients that support remote MCP servers:

Start lazy-mcp in HTTP mode (e.g. `lazy-mcp --config servers.json --transport http --port 3000`), then configure your client:

```json
{
  "mcp": {
    "lazy-mcp": {
      "type": "remote",
      "url": "http://localhost:3000/mcp",
      "headers": {
        "Authorization": "Bearer ${LAZY_MCP_AUTH_TOKEN}"
      }
    }
  }
}
```

Where `~/.config/lazy-mcp/servers.json` contains all 5 servers:
```json
{
  "servers": [
    { "name": "chrome-devtools", "description": "Chrome DevTools automation", "command": ["npx", "-y", "chrome-devtools-mcp@latest"] },
    { "name": "gitlab", "description": "GitLab API integration", "command": ["npx", "mcp-remote@latest", "https://..."] },
    { "name": "grepai", "description": "Search codebase", "command": ["grepai", "mcp-serve"] },
    { "name": "context7", "description": "Library documentation", "command": ["npx", "-y", "@upstash/context7-mcp"] },
    { "name": "perplexity", "description": "Web search", "command": ["npx", "-y", "@perplexity-ai/mcp-server"] }
  ]
}
```

**Result**: ~90% context reduction (from ~16K to ~1.5K tokens initially)

## Example

```bash
# Configure multiple MCP servers in servers.json, then:
npx lazy-mcp@latest --config ~/.config/lazy-mcp/servers.json
# Exposes: list_servers, list_commands, describe_commands, invoke_command (4 meta-tools)
# Instead of loading all tools from all servers upfront (~16K+ tokens),
# the agent discovers tools on-demand (~1.5K tokens initially)
```

## Development

```bash
npm install
npm run build
npm test
```

### Running from Local Source

Instead of `npx lazy-mcp@latest` (which downloads the published package), you can run directly from the cloned repo:

**Without building** — using `ts-node` (picks up source changes immediately):

```bash
npm run dev -- --config ~/.config/lazy-mcp/servers.json
```

**After building** — run the compiled output:

```bash
npm run build
node dist/cli.js --config ~/.config/lazy-mcp/servers.json
# or equivalently:
npm start -- --config ~/.config/lazy-mcp/servers.json
```

**In an MCP client config** — point directly at the local build:

```json
{
  "mcp": {
    "lazy-mcp": {
      "command": "node",
      "args": ["/path/to/lazy-mcp/dist/cli.js", "--config", "~/.config/lazy-mcp/servers.json"]
    }
  }
}
```

Or with `ts-node` (no build needed, always reflects latest source):

```json
{
  "mcp": {
    "lazy-mcp": {
      "command": "npx",
      "args": ["ts-node", "/path/to/lazy-mcp/src/cli.ts", "--config", "~/.config/lazy-mcp/servers.json"]
    }
  }
}
```

## Releases

Releases are fully automated via [semantic-release](https://semantic-release.gitbook.io/) on every push to `main`.

### How It Works

1. CI analyzes all commits since the last tag using [Conventional Commits](https://www.conventionalcommits.org/)
2. Determines the next version (`feat` → minor bump, `fix`/`perf`/`chore`/`refactor`/`test` → patch bump)
3. Updates `package.json`, `CHANGELOG.md`, `VERSION`, and `RELEASE_NOTES.md`
4. Commits those files as `chore(release): X.Y.Z` and pushes a `vX.Y.Z` tag
5. Creates a GitLab Release with the generated release notes
6. The `vX.Y.Z` tag triggers a separate pipeline that publishes the package to npm automatically

No manual version bumping or tagging needed — just merge to `main` with conventional commit messages.

### Required CI/CD Variables

Four CI/CD variables must be configured (GitLab → Project → Settings → CI/CD → Variables):

| Variable | Description |
|----------|-------------|
| `GITLAB_RELEASE_TOKEN` | Project access token — pushes the release commit + tag to `main` and creates the GitLab Release |
| `NPM_TOKEN` | npm automation token — publishes the package to the npm registry on tag pipelines |
| `PYPI_TOKEN` | PyPI API token — publishes the package to PyPI on tag pipelines |
| `CARGO_TOKEN` | crates.io API token — publishes the crate to crates.io on tag pipelines |

#### `GITLAB_RELEASE_TOKEN`

**Creating the token** (GitLab → Project → Settings → Access Tokens):

| Setting | Value |
|---------|-------|
| Token name | `semantic-release-bot` (or any name) |
| Role | **Developer** (push to a protected branch should be configured separately) |
| Scopes | `api`, `write_repository` |

**Adding the variable:**

| Setting | Value |
|---------|-------|
| Key | `GITLAB_RELEASE_TOKEN` |
| Masked | ✅ Yes |
| Protected | ❌ No (must be available on the unprotected `main` pipeline) |

> **Note**: If `main` is a protected branch with push restrictions, the token's bot user must be added to the "Allowed to push" list under GitLab → Project → Settings → Repository → Protected branches.

#### `NPM_TOKEN`

**Creating the token** (npmjs.com → Account → Access Tokens → Generate New Token):

| Setting | Value |
|---------|-------|
| Token type | **Automation** (bypasses 2FA, suitable for CI) |

**Adding the variable:**

| Setting | Value |
|---------|-------|
| Key | `NPM_TOKEN` |
| Masked | ✅ Yes |
| Protected | ✅ Yes (only needed on tag pipelines, which are protected) |

#### `PYPI_TOKEN`

**Creating the token** (pypi.org → Account Settings → API tokens → Add API token):

| Setting | Value |
|---------|-------|
| Token name | `lazy-mcp-ci` (or any name) |
| Scope | **Project: lazy-mcp** (restrict to this project after first publish; use "Entire account" for the very first publish) |

**Adding the variable:**

| Setting | Value |
|---------|-------|
| Key | `PYPI_TOKEN` |
| Masked | ✅ Yes |
| Protected | ✅ Yes (only needed on tag pipelines, which are protected) |

#### `CARGO_TOKEN`

**Creating the token** (crates.io → Account Settings → API Tokens → New Token):

| Setting | Value |
|---------|-------|
| Token name | `lazy-mcp-ci` (or any name) |
| Scopes | `publish-new`, `publish-update` |

**Adding the variable:**

| Setting | Value |
|---------|-------|
| Key | `CARGO_TOKEN` |
| Masked | ✅ Yes |
| Protected | ✅ Yes (only needed on tag pipelines, which are protected) |

## Configuration Reference

### Server Configuration Fields

| Field | Type | Required | Description |
|-------|------|----------|-------------|
| `name` | string | ✅ | Unique server identifier |
| `description` | string | ✅ | Human-readable description |
| `type` | "local" \| "remote" | Optional | Inferred from `url` (remote) or `command` (local) if omitted |
| `command` | string[] \| string | For local | Command to execute (array format recommended) |
| `args` | string[] | Optional | Arguments (only if command is string) |
| `url` | string | For remote | HTTP/HTTPS URL |
| `headers` | object | Optional | Static HTTP headers for remote servers |
| `oauth` | object | Optional | OAuth 2.0 config for remote servers (see below) |
| `env` | object | Optional | Environment variables (supports `${VAR}` and `{file:...}` expansion) |
| `enabled` | boolean | Optional | Enable/disable server (default: true) |
| `examples` | object[] | Optional | Usage examples shown in `list_servers` output |
| `tags` | string[] | Optional | Capability tags for filtering (e.g. `"api"`, `"browser"`) |

### OAuth 2.0 Authentication

lazy-mcp has built-in OAuth 2.0 + PKCE support for remote servers that require user authorization. It works without opening a browser automatically, making it suitable for sandboxed agent environments: when authentication is needed, lazy-mcp returns the authorization URL in the error message so the agent can present it to the user.

OAuth server endpoints are **discovered automatically** via RFC 8414 (`/.well-known/oauth-authorization-server`). Dynamic client registration (RFC 7591) is used when no `clientId` is provided.

Tokens are persisted to `~/.config/lazy-mcp/tokens.json` (mode `0600`) and refreshed automatically via `refresh_token` when available.

**Minimal config** (fully automatic — discovery + dynamic registration):
```json
{
  "name": "glean",
  "description": "Glean enterprise search",
  "url": "https://your-company.glean.com/mcp/default",
  "oauth": {}
}
```

**With a pre-registered client ID**:
```json
{
  "name": "glean",
  "description": "Glean enterprise search",
  "url": "https://your-company.glean.com/mcp/default",
  "oauth": {
    "clientId": "${GLEAN_CLIENT_ID}",
    "extraHeaders": { "X-Glean-Auth-Type": "OAUTH" }
  }
}
```

**`oauth` object fields:**

| Field | Type | Default | Description |
|-------|------|---------|-------------|
| `clientId` | string | — | OAuth client ID. If omitted, dynamic registration (RFC 7591) is attempted |
| `clientSecret` | string | — | Client secret (omit for public-client / PKCE-only flows) |
| `callbackPort` | number | `8947` | Local port for the OAuth redirect callback server |
| `extraHeaders` | object | — | Additional headers added to every authenticated request (e.g. `X-Glean-Auth-Type`) |

**How it works:**

1. Agent calls `invoke_command` (or `list_commands`) on an OAuth-protected server
2. lazy-mcp returns an `isError: true` response with the authorization URL
3. Agent presents the URL to the user: _"Open this URL to authorize Glean: https://..."_
4. User opens the URL in a browser and completes authorization
5. Browser redirects to `http://localhost:8947/callback` — lazy-mcp captures the token
6. Agent retries the original command — now succeeds transparently

### Command Format

**Recommended** (OpenCode-compatible):
```json
{
  "command": ["npx", "-y", "my-mcp-server", "--port", "3000"]
}
```

**Legacy** (still supported):
```json
{
  "command": "npx",
  "args": ["-y", "my-mcp-server", "--port", "3000"]
}
```

### Environment Variables

Use `${VAR_NAME}` to reference environment variables:

```json
{
  "env": {
    "API_KEY": "${MY_API_KEY}",
    "DEBUG": "true"
  },
  "headers": {
    "Authorization": "Bearer ${AUTH_TOKEN}"
  }
}
```

Use `{file:/path/to/secret}` to read a secret directly from a file (trailing newline is stripped automatically). `~/` is expanded to the home directory. On Windows, `%VAR_NAME%` references inside the path are expanded from environment variables (e.g. `%USERPROFILE%`):

```json
{
  "env": {
    "GITLAB_API_TOKEN": "{file:~/.secrets/gl-pat-token}",
    "OTHER_SECRET": "{file:/run/secrets/other-token}"
  },
  "headers": {
    "Authorization": "Bearer {file:~/.secrets/api-token}"
  }
}
```

On Windows you can use `%USERPROFILE%` or any other environment variable in the path:

```json
{
  "env": {
    "API_TOKEN": "{file:%USERPROFILE%\\.secrets\\token}"
  }
}
```

Only absolute paths and `~/` paths are accepted. Relative paths are left unchanged. Both notations can be combined in the same value and work in `env`, `headers`, and `transport.authToken` fields. `${VAR}` references inside a `{file:...}` path are not expanded; use an absolute path, `~/`, or Windows-style `%VAR_NAME%` path expansion instead. If the referenced file cannot be read (missing or permission error), the app exits at startup with an error message — e.g. `Cannot read secret file '/run/secrets/token' (from {file:/run/secrets/token}): ENOENT: no such file or directory`.

**Security best practices for secret files:**

- Set permissions to `0600` (owner read/write only): `chmod 0600 ~/.secrets/my-token`
- Store secret files in a user-specific directory (e.g. `~/.secrets/`)
- Never commit secret files to version control — add them to `.gitignore`

### Transport Configuration

Configure how lazy-mcp exposes its MCP endpoint. By default, it uses stdio (for subprocess-based clients). Set `type: "http"` to run as an HTTP server.

**Top-level configuration** (in `servers.json`):

| Field | Type | Default | Description |
|-------|------|---------|-------------|
| `transport.type` | `"stdio"` \| `"http"` | `"stdio"` | Transport mode |
| `transport.port` | number | `8080` | HTTP server port |
| `transport.host` | string | `"127.0.0.1"` | HTTP server bind address. For TLS-terminating reverse proxies, keep localhost binding and configure `allowedOrigins` explicitly. |
| `transport.path` | string | `"/mcp"` | MCP endpoint URL path |
| `transport.authToken` | string | — | Bearer token for HTTP auth (supports `${VAR}` and `{file:...}` expansion) |
| `transport.allowedOrigins` | string[] | — | List of allowed Origin header values for request-origin validation / CSRF protection (e.g. `["https://example.com"]`). Full origins including scheme and port. Recommended for TLS-terminating reverse-proxy deployments. Does not send CORS response headers. |
| `transport.allowedHosts` | string[] | — | List of explicitly allowed host domains for DNS rebinding protection. If a reverse proxy preserves the public `Host` header, add that host here. |
| `transport.maxPayloadSize` | number | `4194304` | Maximum request body size in bytes. Requests exceeding this limit return HTTP 413 |

**CLI flags** (override config values):

| Flag | Env Variable | Description |
|------|-------------|-------------|
| `--transport` | `LAZY_MCP_TRANSPORT` | Transport type (`stdio` or `http`) |
| `--port` | `LAZY_MCP_PORT` | HTTP server port |
| `--host` | `LAZY_MCP_HOST` | HTTP server bind address |
| `--path` | `LAZY_MCP_PATH` | MCP endpoint URL path |
| `--auth-token` | `LAZY_MCP_AUTH_TOKEN` | Bearer token for HTTP auth |
| `--request-timeout` | `LAZY_MCP_REQUEST_TIMEOUT` | Request timeout in ms for server calls, including MCP handshake requests and remote response parsing (default: 10000) |
| `--max-payload-size` | `LAZY_MCP_MAX_PAYLOAD_SIZE` | Maximum request body size in bytes (default: 4194304) |

When `authToken` is set, all HTTP requests must include `Authorization: Bearer <token>` — unauthenticated requests receive `401 Unauthorized`.

### Logging Configuration

lazy-mcp now emits structured logs to **stderr** (stdout remains reserved for MCP protocol traffic).

**Top-level configuration** (in `servers.json`):

| Field | Type | Default | Description |
|-------|------|---------|-------------|
| `logging.level` | `"error"` \| `"info"` \| `"debug"` | `"info"` | Minimum log level |
| `logging.format` | `"json"` \| `"plain"` | `"json"` | Log output format |
| `logging.dumpBodies` | boolean | `false` | Enable debug request/response body dumps |
| `logging.maxBodyLogBytes` | number | `8192` | Max body-dump size in bytes before truncation |
| `logging.redactKeys` | string[] | — | Additional case-insensitive keys to redact (merged with built-in defaults) |

Built-in redaction includes common secret keys like `authorization`, `token`, `access_token`, `refresh_token`, `client_secret`, and `headers.authorization`.

Example:

```json
{
  "servers": [
    {
      "name": "my-server",
      "description": "Example",
      "command": ["npx", "-y", "my-mcp-server"]
    }
  ],
  "logging": {
    "level": "debug",
    "format": "json",
    "dumpBodies": true,
    "maxBodyLogBytes": 4096,
    "redactKeys": ["my_custom_secret"]
  }
}
```

Typical access log event fields include:
- client source (`clientIp`, optional `forwardedFor`)
- request shape (`httpMethod`, `path`, `mcpMethod`, `lazyTool`)
- downstream routing (`downstreamServer`, `downstreamCommand`)
- outcome (`status`, `reason`, `durationMs`)

### Health Monitoring

lazy-mcp includes a background health monitor that probes all servers periodically. The monitor is **activity-driven**: it sleeps on startup and only begins probing after the first user tool call (`list_servers`, `list_commands`, etc.). After a configurable idle timeout (default: 5 minutes) with no tool calls, the monitor goes back to sleep. This prevents OAuth-protected servers (e.g. GitLab via `mcp-remote`) from opening browser windows when no one is using the tools.

Successful probes populate the discovery cache, so subsequent `list_commands` calls return instantly from cache.

**Top-level configuration** (in `servers.json`):

| Field | Type | Default | Description |
|-------|------|---------|-------------|
| `healthMonitor.enabled` | boolean | `true` | Enable/disable background health monitoring |
| `healthMonitor.interval` | number | `30000` | Interval between health checks (ms) |
| `healthMonitor.timeout` | number | `10000` | Timeout per server probe (ms) |
| `healthMonitor.idleTimeout` | number | `300000` | Stop probing after this much inactivity (ms). `0` = never sleep (legacy) |
| `requestTimeout` | number | `10000` | Timeout for individual server requests. For remote HTTP servers, this includes waiting for headers, reading response bodies, and SSE response parsing. Override via `--request-timeout` or `LAZY_MCP_REQUEST_TIMEOUT` |

To disable health monitoring:
```json
{
  "servers": [...],
  "healthMonitor": { "enabled": false }
}
```

To increase the request timeout (e.g. for slow remote servers):
```json
{
  "servers": [...],
  "requestTimeout": 30000
}
```

### Config Reload (SIGHUP)

You can reload the configuration without restarting the process by sending a `SIGHUP` signal:

```bash
kill -HUP $(pgrep -f lazy-mcp)
```

This will:
- Re-read and validate the config file
- Add newly configured servers (lazy connection on first use)
- Remove servers no longer in config (closes connections)
- Reconnect servers whose config changed (updated URL, env, etc.)
- Preserve unchanged servers (keeps existing connections and caches)
- Restart the health monitor and probe all servers

If the new config is invalid, the reload is rejected and the current config continues running. All reload activity is logged to stderr.

> **Note**: SIGHUP is not available on Windows.

## Benefits

- **90%+ context reduction** - From ~16K to ~1.5K tokens initially
- **Progressive tool discovery** - Only load schemas when needed
- **Multi-server aggregation** - Manage multiple MCP servers in one config
- **Batch discovery** - Discover multiple servers efficiently
- **Scales to hundreds** of commands without context bloat
- **Flexible configuration** - Enable/disable servers on demand
- **Environment variable support** - Secure credential management via `${VAR}` and `{file:...}` notations
- **Both local and remote** - Support for subprocess and HTTP servers
- **Streamable HTTP transport** - Run as an HTTP server for remote client access
- **Health monitoring** - Background probes detect broken servers before you hit them

## Documentation

- **[CHANGELOG.md](./CHANGELOG.md)** - Version history and release notes
- **[AGENTS.md](./AGENTS.md)** - Development guide for AI coding agents (build commands, code style, testing patterns)
- **[doc/ARCHITECTURE.md](./doc/ARCHITECTURE.md)** - Architecture overview and design patterns
- **[doc/CONTRIBUTING.md](./doc/CONTRIBUTING.md)** - Contributing guide with common development tasks
- **[doc/requests/](./doc/requests/)** - [Bruno](https://www.usebruno.com/) API collection for testing the Streamable HTTP transport. Open the `doc/requests/` folder as a collection in Bruno, select the `local` or `local-with-auth` environment, and run requests against a locally running `lazy-mcp --transport http` instance.
- **[Configuration Reference](#configuration-reference)** - Server configuration options (above)
