mcp_filesystem.md

MCP example: a filesystem server over stdio

The smallest useful mcp.json: the MCP org's reference filesystem server, scoped to the directory you launch CoreCoder from. The agent gains mcp__fs__* tools (read/write/list inside that one directory) while CoreCoder's own consent gate and hooks keep applying to every call.

Use it

Merge the entry into ~/.corecoder/mcp.json (create the file if it does not exist; if you already have servers, add "fs" next to them):

{
  "mcpServers": {
    "fs": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "."]
    }
  }
}

Requires Node.js on PATH (npx). The first launch downloads the server package, which can outlast the 15-second handshake budget; if /mcp shows the server as dead on first run, /mcp reconnect fs picks it up once the npx cache is warm, and every later start is fast.

The "." argument is resolved by the server itself, so launch CoreCoder from the directory you want exposed. To expose a fixed tree instead, put an absolute path there. Anything outside the listed directories is refused by the server, not by CoreCoder.

What you should see

/mcp lists fs as connected with its tool count, and asking the agent to "show me what's in this directory" now routes through mcp__fs__list_directory with the usual consent prompt, since MCP tools never join the read-only set.

Remove it

Delete the "fs" entry from ~/.corecoder/mcp.json and restart. No state is kept anywhere else.