MCP server

gko mcp serve exposes configured business commands over stdio. Configure an MCP client to launch the gko executable with arguments mcp, serve, optionally preceded by --config-dir DIR. Standard output contains only MCP messages; diagnostics go to stderr.

The server supports MCP 2026-07-28: start with server/discover, then use tools/list and tools/call with the required per-request _meta. Legacy initialize negotiation is not supported. Only the tools capability is advertised. No MCP client, sampling, prompts, resources, or hot reload is provided.

Each command path becomes a tool name by joining its segments with _. Name collisions are fatal at startup and report both command files. Tool arguments come from typed [args.*]: enums, bounded integers, strings, and file content. Send the command's main text as the literal "mcp.input" property. It remains distinct from a configured input argument. Unknown, missing, or incorrectly typed properties are rejected before a backend request. A command with [input] mode = "binary" is not exposed: tool arguments are JSON, not bytes.

Successful calls return the finalized command output as text. JSON output is additionally returned in structuredContent when it is an object, always the whole document: [output].extract applies to the CLI only. A JSON answer that is not an object (an embeddings vector, for one) is returned as text only, and a command whose output schema's root is not type = "object" advertises no outputSchema. Pipeline failures have isError: true and a structured error envelope in structuredContent. If configuration loading fails, discovery explains the error and recommends gko doctor; tools/list is empty. Restart the server after editing configuration.

Tool calls run one at a time. The server never starts a runtime: start the backend with gko backend serve first.