Firefox MCP Server

Instructions

Implementation Reference

• index-multi-debug.js:1008-1019 (handler)

  The core handler function for the 'set_active_tab' tool. It validates the tab exists, sets it as the active tab (this.activeTabId = tabId), and returns a success message.

  async setActiveTab(args) {
    const { tabId } = args;
    
    if (!this.pages.has(tabId)) {
      throw new Error(`Tab '${tabId}' not found`);
    }
  
    this.activeTabId = tabId;
    return {
      content: [{ type: 'text', text: `Active tab set to '${tabId}'` }]
    };
  }

• index-multi-debug.js:260-268 (registration)

  Registers the 'set_active_tab' tool in the tools list provided to ListToolsRequestSchema, including name, description, and input schema.

  {
    name: 'set_active_tab',
    description: 'Set active tab',
    inputSchema: {
      type: 'object',
      properties: { tabId: { type: 'string' } },
      required: ['tabId']
    }
  },

• index-multi-debug.js:263-266 (schema)

  Defines the input schema for the 'set_active_tab' tool, requiring a 'tabId' string.

  inputSchema: {
    type: 'object',
    properties: { tabId: { type: 'string' } },
    required: ['tabId']

• index-multi-debug.js:405-406 (handler)

  Dispatches calls to the 'set_active_tab' tool to the setActiveTab method within the central CallToolRequestSchema handler.

  case 'set_active_tab':
    return await this.setActiveTab(args);