---
title: MCP servers
description: Connect MCP servers with the same JSON you use elsewhere; their tools join the agent's toolbox and ask before running.
---
# MCP servers

Lampson is an MCP client. Any server that speaks MCP over stdio — GitHub, a database, a browser, your own — can be plugged in, and its tools become available to the agent.

## Adding one

- **Terminal**: `/mcp add github npx -y @modelcontextprotocol/server-github`
- **Web**: **MCP** in the left panel → `+ nuevo`.
- **Ask the agent**: "add the GitHub MCP server" — it fills in the config and asks you to confirm.

Or write the file yourself. It is the same format as other tools:

```json
{"mcpServers": {"github": {"command": "npx", "args": ["-y", "@modelcontextprotocol/server-github"],
                           "env": {"GITHUB_TOKEN": "…"}}}}
```

- `~/lampson/.lampson/mcp.json` is **global** — one config, every project you open.
- `<project>/.lampson/mcp.json` is per project; a server with the same name overrides the global one.
- `"disabled": true` keeps an entry without starting it. `"cwd"` defaults to the project folder.

## How it behaves

- Each server starts when Lampson does and is supervised; one that dies shows `error` in `/mcp` and the panel.
- Its tools appear to the model as `mcp_<server>_<tool>`. `build` and `worker` see all of them; the read-only profiles only see those the server marks read-only.
- Every call goes through [permissions](/en/docs/permissions): **asks** by default, runs in `yolo`, denied in `strict`. Every call is in the session trace.

Not yet supported: HTTP/SSE transports, resources and prompts.