Firefox MCP Server

Instructions

Implementation Reference

• index-multi-debug.js:981-1006 (handler)

  The main handler function for the 'close_tab' tool. It closes the specified tab's page, removes it from the pages map, clears associated debug buffers, updates the active tab if necessary, and returns a success message.

  async closeTab(args) {
    const { tabId } = args;
    
    if (!this.pages.has(tabId)) {
      throw new Error(`Tab '${tabId}' not found`);
    }
  
    const page = this.pages.get(tabId);
    await page.close();
    this.pages.delete(tabId);
    
    // Clear debug buffers
    this.clearTabDebugBuffers(tabId);
  
    // If this was the active tab, clear active tab
    if (this.activeTabId === tabId) {
      this.activeTabId = this.pages.size > 0 ? Array.from(this.pages.keys())[0] : null;
    }
  
    return {
      content: [{
        type: 'text',
        text: `Tab '${tabId}' closed and debug buffers cleared.${this.activeTabId ? ` Active tab is now '${this.activeTabId}'` : ''}`
      }]
    };
  }

• index-multi-debug.js:403-404 (registration)

  Dispatch/registration in the tool request handler switch statement, which calls the closeTab method when 'close_tab' is invoked.

  case 'close_tab':
    return await this.closeTab(args);

• index-multi-debug.js:78-84 (schema)

  Tool schema definition in the listTools response, specifying the name, description, and input schema requiring 'tabId'.

  name: 'close_tab',
  description: 'Close a specific tab',
  inputSchema: {
    type: 'object',
    properties: { tabId: { type: 'string' } },
    required: ['tabId']
  }

• index-multi-debug.js:477-483 (helper)

  Helper method called by closeTab to clear debug buffers associated with the closed tab.

  clearTabDebugBuffers(tabId) {
    this.consoleLogs.delete(tabId);
    this.jsErrors.delete(tabId);
    this.networkActivity.delete(tabId);
    this.wsMessages.delete(tabId);
    this.performanceMetrics.delete(tabId);
  }