Choose the tools a client can call

github.com/libtmux/libtmux-go/mcp · Source

Tool selection is evaluated at startup. Only advertised tools can be called directly. A selected batch tool can also invoke its permitted nested operations, as described below. Changing the environment requires a new server process and connection.

Toolsets¶

LIBTMUX_TOOLSETS accepts a comma-separated selection:

With no explicit selection, an existing or explicitly selected endpoint uses inspect,manage,execute. The default dedicated daemon gains teardown only when the launcher verifies that its own minimal-config startup created it. An explicit inspect selection remains inspection-only regardless of that ownership result.

A present but empty LIBTMUX_TOOLSETS selects no toolsets. An unset variable uses defaults. There is no none sentinel. Leading, trailing, and interior empty list items are errors, as are unknown names. Validate configuration before reconnecting a client that depends on it.

Exact tools and exclusions¶

LIBTMUX_TOOLS adds exact names after expanding toolsets. LIBTMUX_EXCLUDE_TOOLS removes names last, even if another selection included them. For a connected command-only client, the complete command example uses an empty toolset plus LIBTMUX_TOOLS=run_shell_command.

To allow session metadata without the rest of inspect, set these values in the client’s environment:

{
  "LIBTMUX_TOOLSETS": "",
  "LIBTMUX_TOOLS": "list_sessions"
}

call_read_tools_batch has its own set of permitted nested operations. Selecting that batch by name includes those operations even when they are absent from top-level discovery. For example, an empty toolset plus LIBTMUX_TOOLS=call_read_tools_batch exposes the batch and its nested reads without exposing those reads as separate tools.

LIBTMUX_EXCLUDE_TOOLS also removes operations from the batch’s advertised schema and dispatch. Exclude an operation explicitly when it must be unavailable through both paths. Inspect the batch schema before constructing a request.

Inspect the active selection¶

Read tmux://capabilities and compare it with the client’s tool discovery. The resource records the effective names, selection, connection provenance, and capability rows also attached to each tool’s metadata. It is a startup snapshot. Use list_sessions and list_panes for current topology.

The selection resolver and capability catalog define names, schemas, and expansion. The tool reference describes individual arguments and results.

Terminal input¶

Inspection can reveal terminal content and configuration. Input and execution run with the tmux user’s authority; choosing a socket does not confine a shell command’s effects to tmux. Choose the smallest useful selection for the task.

The input handlers also check the target’s current mode and synchronized-pane membership. A tool may require client interaction before input is sent, or refuse a dead or unsuitable target. If the client cannot complete the requested interaction, treat the tool error as a failed operation; do not infer success from the tool being present in discovery.

See the input handlers and input checks for the selected release’s behavior.