Completion¶

libtmux-mcp inherits FastMCP’s built-in MCP completion behaviour. We don’t hand-author completion providers — the argument shapes on our prompts and resource templates are what the client sees.

What the spec does¶

A client calls completion/complete with a partial argument for a prompt or resource URI template; the server replies with up to 100 suggestions. Agents use this to offer auto-complete UX — e.g. a session picker popup when filling session_name= on get_session.

What libtmux-mcp currently exposes¶

Prompt arguments — the four recipes (Prompts) advertise their argument names and types. FastMCP derives a default completion shape from the Python signatures: str arguments accept free text, float arguments accept numeric strings, no enum / list suggestions.
Resource template parameters — Resources URIs carry {session_name}, {window_index}, {pane_id}, and {?socket_name} placeholders. Completion suggestions are again derived from the function signatures’ types, not from live tmux state.

Warning

libtmux-mcp does not currently wire completion back to live tmux enumeration — i.e. the completion for session_name will not return the names of sessions that exist on the server right now. Adding that requires a dedicated FastMCP completion handler; tracked as a potential enhancement.

Workarounds for clients that need live enumeration¶

Agents that need to pick a real session / window / pane can call list_sessions readonly, list_windows readonly, or list_panes readonly directly before rendering a prompt, then feed the chosen ID back into the prompt’s arguments.