Crate tmux_mcp 

A Model Context Protocol server exposing tmux through libtmux.

The server freezes one 45-tool surface at startup from the unordered inspect, manage, execute, and teardown toolsets. Every native route carries its process reach, tmux effects, output classes, interpreter sinks, and whole-call annotations in one typed manifest. The effective manifest is available as tmux://capabilities.

The dependency runs one way. libtmux knows nothing about MCP.

Startup boundary

One process selects one socket. The binary uses the dedicated libtmux-mcp socket and minimal configuration by default; explicit socket or configuration settings carry conservative provenance. Teardown is in the implicit default only for a newly dedicated minimal daemon. The LIBTMUX_TOOLSETS, LIBTMUX_TOOLS, and LIBTMUX_EXCLUDE_TOOLS settings are parsed before tmux access, and exclusions win.

Trust boundary

Pane input and pane commands run with the tmux user’s permissions. Pane output may be sensitive or untrusted. tmux environment values are withheld unless Builder::environment_values allows the name; hooks may contain executable configuration. Configured-process routes accept neither command nor environment payloads. There is no public host-command route.

Knowing where you are

An inherited TMUX and TMUX_PANE identify the caller only after socket provenance matches. Pane listings report self, other, or unknown, and pane-input and teardown routes fail closed when their reach may contain the caller.

Modules

cli

Reading the command line the binary was started with.

resources

The frozen capability report exposed as one static MCP resource.

Macros

capability_meta

Attach one typed capability row to an SDK-native tool route.

Structs

Branch

One session with everything under it.

BranchPane

One pane inside a described window.

BranchWindow

One window inside a described session.

Builder

Assembles a TmuxTools with the parts the environment usually supplies.

CallerIdentity

The tmux pane hosting this process, as its environment describes it.

CapabilityReport

The frozen, effective MCP surface reported at tmux://capabilities.

Capture

What a pane is showing.

CapturePaneArgs

Arguments for reading a pane.

CaptureSinceArgs

Arguments for reading what a pane wrote since last time.

ChannelArgs

Arguments naming a wait-for channel.

ChannelSignal

A channel that was signalled.

ChannelWait

How a wait on a channel finished.

CreateSessionArgs

Arguments for creating a session.

Cursor

A place in one pane’s output.

Environment

A tmux environment, server-wide or for one session.

EnvironmentEntry

One tmux environment entry.

Hook

One tmux hook.

Hooks

The hooks set at one scope.

Killed

An object that was destroyed.

Layout

A window whose layout was set.

MatchView

One line of one pane that matched a search.

Matches

Where a pattern was found.

OptionArgs

Arguments for reading a tmux option.

OptionValue

The value of one tmux option.

PaneArgs

Arguments naming one pane.

PaneChanged

A pane that was cleared, respawned, or retitled.

PaneView

One pane, as the protocol sees it.

Panes

Every pane asked for.

PasteTextArgs

Arguments for putting text into a pane without typing it.

Pasted

Text that was pasted into a pane.

Reporter

Whoever asked to be told how a long call is getting on.

ResizePaneArgs

Arguments for resizing a pane.

RunCommandArgs

Arguments for running a command and waiting for it.

RunView

What a command did.

SearchPanesArgs

Arguments for searching what panes are showing.

SelectLayoutArgs

Arguments for arranging a window’s panes.

SelectPaneArgs

Arguments for moving focus between panes.

SelectWindowArgs

Arguments for moving focus between windows.

Selection

The startup-frozen request for one MCP tool surface.

SendKeysArgs

Arguments for sending input to a pane.

Sent

Keys that were sent.

SessionArgs

Arguments naming one session.

SessionView

One session, as the protocol sees it.

Sessions

Every session on the server.

ShowEnvironmentArgs

Arguments for reading a tmux environment.

ShowHooksArgs

Arguments for reading the hooks set at a scope.

Since

What a pane wrote since a cursor.

Size

A pane’s size after being resized.

Snapshot

A pane’s contents and the state a capture leaves out.

SnapshotArgs

Arguments for reading a pane’s whole state.

SurfaceError

A startup configuration or manifest error.

TmuxTools

A tmux server presented as MCP tools.

ToolError

A tool-execution failure, reported as isError tool content.

Tree

The whole hierarchy, in one answer.

WaitForTextArgs

Arguments for waiting until a pane says something.

WaitView

What a pane said while it was watched for a pattern.

WindowArgs

Arguments naming one window.

WindowView

One window, as the protocol sees it.

Windows

Every window asked for.

Enums

EnvironmentState

What tmux holds under one environment name.

Marks

Whether tmux knew where the last command’s output began.

Relation

How a pane relates to the process answering the request.

RunOutcome

How a run finished.

SocketProvenance

What startup can honestly claim about the selected tmux daemon.

Toolset

One mechanical group in the advertised MCP tool inventory.

WaitOutcome

How a wait for text finished.

Constants

ENVIRONMENT_VALUES_ENV

The tmux environment variables whose values tools may return.

EXCLUDE_TOOLS_ENV

Individual tools removed after every inclusion path.

RETIRED_RUST_SAFETY_ENV

The older Rust-specific safety setting, rejected rather than ignored.

RETIRED_SAFETY_ENV

The retired ordered-safety setting, rejected rather than ignored.

TOOLSETS_ENV

The unordered toolsets enabled for this process.

TOOLS_ENV

Individual tools added after toolset expansion.

Functions

environment_values_from_env

Read ENVIRONMENT_VALUES_ENV before serving MCP.

parse_environment_values

Parse the operator’s allowed environment names.