Tmux MCP Server

Instructions

Implementation Reference

• src/index.ts:386-401 (handler)

  The core handler function for the tmux_kill_window tool. It constructs the tmux target from session and window identifiers, executes the 'tmux kill-window' command using the runTmux helper, and returns success/error responses.

  async ({ session, window }) => {
    try {
      const target = formatTarget(session, window);
      await runTmux(`kill-window -t "${target}"`);
  
      return {
        content: [{ type: "text", text: `Window '${window}' in session '${session}' killed successfully.` }],
        structuredContent: { success: true, session, window },
      };
    } catch (error) {
      return {
        content: [{ type: "text", text: error instanceof Error ? error.message : String(error) }],
        isError: true,
      };
    }
  }

• src/index.ts:373-378 (schema)

  Zod input schema defining parameters: session (string) and window (string or number).

  inputSchema: z
    .object({
      session: z.string().min(1).describe("Name of the session"),
      window: z.union([z.string(), z.number()]).describe("Window index or name"),
    })
    .strict(),

• src/index.ts:362-402 (registration)

  Full registration of the tmux_kill_window tool with McpServer, including name, metadata, schema, annotations, and handler reference.

  server.registerTool(
    "tmux_kill_window",
    {
      title: "Kill tmux Window",
      description: `Kill (close) a window in a tmux session.
  
  Args:
    - session (string, required): Name of the session
    - window (string or number, required): Window index or name
  
  WARNING: This will terminate all processes running in the window.`,
      inputSchema: z
        .object({
          session: z.string().min(1).describe("Name of the session"),
          window: z.union([z.string(), z.number()]).describe("Window index or name"),
        })
        .strict(),
      annotations: {
        readOnlyHint: false,
        destructiveHint: true,
        idempotentHint: true,
        openWorldHint: false,
      },
    },
    async ({ session, window }) => {
      try {
        const target = formatTarget(session, window);
        await runTmux(`kill-window -t "${target}"`);
  
        return {
          content: [{ type: "text", text: `Window '${window}' in session '${session}' killed successfully.` }],
          structuredContent: { success: true, session, window },
        };
      } catch (error) {
        return {
          content: [{ type: "text", text: error instanceof Error ? error.message : String(error) }],
          isError: true,
        };
      }
    }
  );

• src/index.ts:70-81 (helper)

  Helper function used by the handler to format the tmux target string (e.g., 'session:window.pane').

  function formatTarget(session?: string, window?: number | string, pane?: number): string {
    let target = "";
    if (session) {
      target = session;
      if (window !== undefined) {
        target += `:${window}`;
        if (pane !== undefined) {
          target += `.${pane}`;
        }
      }
    }
    return target;

• src/index.ts:45-67 (helper)

  Core helper utility to execute tmux commands asynchronously, with custom error messages for common tmux failures.

  async function runTmux(args: string): Promise<string> {
    try {
      const { stdout } = await execAsync(`tmux ${args}`);
      return stdout.trim();
    } catch (error: unknown) {
      if (error instanceof Error && "stderr" in error) {
        const stderr = (error as { stderr: string }).stderr;
        if (stderr.includes("no server running")) {
          throw new Error("tmux server is not running. Start a session first with tmux_create_session.");
        }
        if (stderr.includes("session not found")) {
          throw new Error("Session not found. Use tmux_list_sessions to see available sessions.");
        }
        if (stderr.includes("window not found")) {
          throw new Error("Window not found. Use tmux_list_windows to see available windows.");
        }
        if (stderr.includes("can't find pane")) {
          throw new Error("Pane not found. Use tmux_list_panes to see available panes.");
        }
        throw new Error(`tmux error: ${stderr}`);
      }
      throw error;
    }