Runs the Model Context Protocol server: one JSON-RPC message per line on stdin, one answer per line on stdout, until stdin closes.
This is what an MCP client launches, so it says nothing on stdout that is not a
protocol message — a stray IO.puts here is a message the client cannot parse.
Anything worth saying goes to stderr.
# .mcp.json / mcp.json, in a project that depends on ex_cadmpeg
{"mcpServers": {"cadmpeg": {"command": "mix", "args": ["cadmpeg.mcp"]}}}The tools are Cadmpeg.Mcp.Tools; what the server is for is in Cadmpeg.Mcp.