Tmux MCP Server

Instructions

Implementation Reference

• src/index.ts:889-905 (handler)

  The handler function executes the tmux resize-pane command based on the provided direction and amount, targeting the specified session, window, and pane.

  async ({ session, window, pane, direction, amount }) => {
    try {
      const target = formatTarget(session, window, pane);
      const dirFlag = { up: "-U", down: "-D", left: "-L", right: "-R" }[direction];
      await runTmux(`resize-pane -t "${target}" ${dirFlag} ${amount}`);
  
      return {
        content: [{ type: "text", text: `Pane resized ${direction} by ${amount} cells.` }],
        structuredContent: { success: true, direction, amount },
      };
    } catch (error) {
      return {
        content: [{ type: "text", text: error instanceof Error ? error.message : String(error) }],
        isError: true,
      };
    }
  }

• src/index.ts:873-881 (schema)

  Zod input schema defining parameters: session (required string), window and pane (optional), direction (enum: up/down/left/right), amount (int >=1, default 5).

  inputSchema: z
    .object({
      session: z.string().min(1).describe("Name of the session"),
      window: z.union([z.string(), z.number()]).optional().describe("Window index or name"),
      pane: z.number().int().min(0).optional().describe("Pane index"),
      direction: z.enum(["up", "down", "left", "right"]).describe("Direction to resize"),
      amount: z.number().int().min(1).default(5).describe("Number of cells to resize by"),
    })
    .strict(),

• src/index.ts:861-906 (registration)

  Full registration of the tmux_resize_pane tool with McpServer, including title, description, input schema, annotations, and handler function.

  server.registerTool(
    "tmux_resize_pane",
    {
      title: "Resize tmux Pane",
      description: `Resize a pane in a tmux window.
  
  Args:
    - session (string, required): Name of the session
    - window (string or number, optional): Window index or name
    - pane (number, optional): Pane index
    - direction (string, required): Direction to resize: up, down, left, right
    - amount (number, optional): Number of cells to resize by (default: 5)`,
      inputSchema: z
        .object({
          session: z.string().min(1).describe("Name of the session"),
          window: z.union([z.string(), z.number()]).optional().describe("Window index or name"),
          pane: z.number().int().min(0).optional().describe("Pane index"),
          direction: z.enum(["up", "down", "left", "right"]).describe("Direction to resize"),
          amount: z.number().int().min(1).default(5).describe("Number of cells to resize by"),
        })
        .strict(),
      annotations: {
        readOnlyHint: false,
        destructiveHint: false,
        idempotentHint: false,
        openWorldHint: false,
      },
    },
    async ({ session, window, pane, direction, amount }) => {
      try {
        const target = formatTarget(session, window, pane);
        const dirFlag = { up: "-U", down: "-D", left: "-L", right: "-R" }[direction];
        await runTmux(`resize-pane -t "${target}" ${dirFlag} ${amount}`);
  
        return {
          content: [{ type: "text", text: `Pane resized ${direction} by ${amount} cells.` }],
          structuredContent: { success: true, direction, amount },
        };
      } catch (error) {
        return {
          content: [{ type: "text", text: error instanceof Error ? error.message : String(error) }],
          isError: true,
        };
      }
    }
  );