Connect GitHub Copilot CLI to Semlith over MCP

How to connect GitHub Copilot CLI to Semlith over MCP, the command or file that adds it, and how to check the connection works.

Every stanza writes ${SEMLITH_BIN} where the binary goes, the path which semlith prints. Set up your agent client explains it and the HTTP form.

GitHub Copilot CLI — ~/.copilot/mcp-config.json, or /mcp add in a session. Its name for a subprocess is local rather than stdio; a remote server is http. copilot mcp add has no scope flag and always writes the user configuration at ~/.copilot/mcp-config.json, which covers every repository; a per-repository entry means editing .mcp.json by hand — see https://docs.github.com/en/copilot/how-tos/copilot-cli/customize-copilot/add-mcp-servers.

~/.copilot/mcp-config.json

{
  "mcpServers": {
    "semlith": {
      "type": "local",
      "command": "${SEMLITH_BIN}",
      "args": ["mcp"],
      "tools": ["*"],
      "deferTools": "never"
    }
  }
}

Or against a daemon on another machine, over HTTP:

{
  "mcpServers": {
    "semlith": {
      "type": "http",
      "url": "http://127.0.0.1:7365/mcp",
      "headers": { "Authorization": "Bearer ${SEMLITH_AGENT_KEY}" },
      "tools": ["*"]
    }
  }
}

copilot mcp add --transport http semlith http://127.0.0.1:7365/mcp --header "Authorization: Bearer ${SEMLITH_AGENT_KEY}"

To replace an existing entry:

copilot mcp remove semlith

copilot mcp add semlith -- "${SEMLITH_BIN}" mcp

Its user-level instructions file, read on every session, to which semlith setup --register-all appends the rule block — see https://docs.github.com/en/copilot/how-tos/copilot-cli/customize-copilot/add-custom-instructions.

~/.copilot/copilot-instructions.md

${SEMLITH_RULES}