Firefox MCP Server

Instructions

Implementation Reference

• index-multi-debug.js:858-890 (handler)

  The main handler function that clears the debug buffers (console logs, JS errors, network activity, WebSocket messages) for a specific tab or all types. Resets the internal Maps/arrays to empty and clears injected page variables.
  async clearDebugBuffers(args = {}) { const { tabId, types } = args; const effectiveTabId = tabId || this.activeTabId; if (!types || types.length === 0) { // Clear all buffers this.consoleLogs.set(effectiveTabId, []); this.jsErrors.set(effectiveTabId, []); this.networkActivity.set(effectiveTabId, []); // Clear WebSocket messages if (this.pages.has(effectiveTabId)) { const page = this.pages.get(effectiveTabId); await page.evaluate(() => { window._wsMessages = []; }); } } else { // Clear specific buffers if (types.includes('console')) this.consoleLogs.set(effectiveTabId, []); if (types.includes('errors')) this.jsErrors.set(effectiveTabId, []); if (types.includes('network')) this.networkActivity.set(effectiveTabId, []); if (types.includes('websocket') && this.pages.has(effectiveTabId)) { const page = this.pages.get(effectiveTabId); await page.evaluate(() => { window._wsMessages = []; }); } } return { content: [{ type: 'text', text: `Debug buffers cleared for tab '${effectiveTabId}': ${types ? types.join(', ') : 'all'}` }] }; }
• index-multi-debug.js:350-363 (schema)

  The tool definition including input schema for tabId (optional) and types array to specify which buffers to clear.
  { name: 'clear_debug_buffers', description: 'Clear debug event buffers for a tab', inputSchema: { type: 'object', properties: { tabId: { type: 'string' }, types: { type: 'array', items: { type: 'string', enum: ['console', 'errors', 'network', 'websocket'] } } } } },
• index-multi-debug.js:451-452 (registration)

  Dispatch case in the CallToolRequestSchema handler that routes the tool call to the clearDebugBuffers method.
  case 'clear_debug_buffers': return await this.clearDebugBuffers(args);
• index-multi-debug.js:43-389 (registration)

  Registration of the tool list including clear_debug_buffers in the ListToolsRequestSchema response.
  this.server.setRequestHandler(ListToolsRequestSchema, async () => { return { tools: [ // Original tools (abbreviated for space) { name: 'launch_firefox_multi', description: 'Launch Firefox browser with multi-tab support and debugging', inputSchema: { type: 'object', properties: { headless: { type: 'boolean', default: false }, enableDebugLogging: { type: 'boolean', default: true } } } }, { name: 'create_tab', description: 'Create a new tab with isolated session and debugging', inputSchema: { type: 'object', properties: { tabId: { type: 'string' }, url: { type: 'string', default: 'about:blank' }, contextId: { type: 'string' }, enableMonitoring: { type: 'boolean', default: true } }, required: ['tabId'] } }, { name: 'list_tabs', description: 'List all active tabs', inputSchema: { type: 'object', properties: {} } }, { name: 'close_tab', description: 'Close a specific tab', inputSchema: { type: 'object', properties: { tabId: { type: 'string' } }, required: ['tabId'] } }, { name: 'navigate', description: 'Navigate to a URL', inputSchema: { type: 'object', properties: { url: { type: 'string' }, tabId: { type: 'string' } }, required: ['url'] } }, { name: 'click', description: 'Click on an element', inputSchema: { type: 'object', properties: { selector: { type: 'string' }, coordinates: { type: 'object', properties: { x: { type: 'number' }, y: { type: 'number' } } }, tabId: { type: 'string' } } } }, { name: 'type_text', description: 'Type text into an input field', inputSchema: { type: 'object', properties: { selector: { type: 'string' }, text: { type: 'string' }, tabId: { type: 'string' } }, required: ['selector', 'text'] } }, { name: 'send_key', description: 'Send keyboard events', inputSchema: { type: 'object', properties: { key: { type: 'string' }, selector: { type: 'string' }, modifiers: { type: 'array', items: { type: 'string' } }, repeat: { type: 'number', default: 1 }, tabId: { type: 'string' } }, required: ['key'] } }, { name: 'drag', description: 'Perform drag operation', inputSchema: { type: 'object', properties: { selector: { type: 'string' }, fromCoordinates: { type: 'object', properties: { x: { type: 'number' }, y: { type: 'number' } } }, toCoordinates: { type: 'object', properties: { x: { type: 'number' }, y: { type: 'number' } } }, offsetX: { type: 'number' }, offsetY: { type: 'number' }, duration: { type: 'number', default: 0 }, steps: { type: 'number', default: 1 }, tabId: { type: 'string' } } } }, { name: 'execute_script', description: 'Execute JavaScript in the browser', inputSchema: { type: 'object', properties: { script: { type: 'string' }, tabId: { type: 'string' } }, required: ['script'] } }, { name: 'screenshot', description: 'Take a screenshot', inputSchema: { type: 'object', properties: { path: { type: 'string', default: 'screenshot.png' }, fullPage: { type: 'boolean', default: false }, tabId: { type: 'string' } } } }, { name: 'get_page_content', description: 'Get HTML content', inputSchema: { type: 'object', properties: { selector: { type: 'string' }, tabId: { type: 'string' } } } }, { name: 'get_page_text', description: 'Get visible text content', inputSchema: { type: 'object', properties: { selector: { type: 'string' }, tabId: { type: 'string' } } } }, { name: 'wait_for_element', description: 'Wait for element to appear', inputSchema: { type: 'object', properties: { selector: { type: 'string' }, timeout: { type: 'number', default: 30000 }, tabId: { type: 'string' } }, required: ['selector'] } }, { name: 'close_browser', description: 'Close browser and all tabs', inputSchema: { type: 'object', properties: {} } }, { name: 'get_current_url', description: 'Get current page URL', inputSchema: { type: 'object', properties: { tabId: { type: 'string' } } } }, { name: 'back', description: 'Navigate back', inputSchema: { type: 'object', properties: { tabId: { type: 'string' } } } }, { name: 'forward', description: 'Navigate forward', inputSchema: { type: 'object', properties: { tabId: { type: 'string' } } } }, { name: 'reload', description: 'Reload page', inputSchema: { type: 'object', properties: { tabId: { type: 'string' } } } }, { name: 'set_active_tab', description: 'Set active tab', inputSchema: { type: 'object', properties: { tabId: { type: 'string' } }, required: ['tabId'] } }, // NEW DEBUG TOOLS { name: 'get_console_logs', description: 'Get captured console logs from browser', inputSchema: { type: 'object', properties: { tabId: { type: 'string' }, since: { type: 'number', description: 'Timestamp to filter logs since' }, types: { type: 'array', items: { type: 'string', enum: ['log', 'error', 'warn', 'info', 'debug'] }, description: 'Filter by log types' }, limit: { type: 'number', default: 50, description: 'Max number of logs to return' } } } }, { name: 'get_javascript_errors', description: 'Get captured JavaScript errors', inputSchema: { type: 'object', properties: { tabId: { type: 'string' }, since: { type: 'number' }, limit: { type: 'number', default: 20 } } } }, { name: 'get_network_activity', description: 'Get captured network requests and responses', inputSchema: { type: 'object', properties: { tabId: { type: 'string' }, since: { type: 'number' }, filter: { type: 'string', enum: ['all', 'xhr', 'websocket', 'fetch'], default: 'all' }, limit: { type: 'number', default: 30 } } } }, { name: 'get_websocket_messages', description: 'Get captured WebSocket messages (for LiveView debugging)', inputSchema: { type: 'object', properties: { tabId: { type: 'string' }, since: { type: 'number' }, limit: { type: 'number', default: 50 } } } }, { name: 'get_performance_metrics', description: 'Get performance metrics (timing, memory usage)', inputSchema: { type: 'object', properties: { tabId: { type: 'string' } } } }, { name: 'start_monitoring', description: 'Start/restart monitoring for a tab', inputSchema: { type: 'object', properties: { tabId: { type: 'string' }, types: { type: 'array', items: { type: 'string', enum: ['console', 'errors', 'network', 'websocket', 'performance'] }, default: ['console', 'errors', 'network', 'websocket'] } } } }, { name: 'clear_debug_buffers', description: 'Clear debug event buffers for a tab', inputSchema: { type: 'object', properties: { tabId: { type: 'string' }, types: { type: 'array', items: { type: 'string', enum: ['console', 'errors', 'network', 'websocket'] } } } } }, { name: 'get_all_debug_activity', description: 'Get combined feed of all debug events', inputSchema: { type: 'object', properties: { tabId: { type: 'string' }, since: { type: 'number' }, limit: { type: 'number', default: 100 } } } }, { name: 'inject_debugging_helpers', description: 'Inject debugging helper functions into the page', inputSchema: { type: 'object', properties: { tabId: { type: 'string' }, includeWebSocketMonitoring: { type: 'boolean', default: true } } } } ], }; });
• index-multi-debug.js:477-483 (helper)

  Helper method to completely delete (not just clear) debug buffers for a tab, used when closing tabs.
  clearTabDebugBuffers(tabId) { this.consoleLogs.delete(tabId); this.jsErrors.delete(tabId); this.networkActivity.delete(tabId); this.wsMessages.delete(tabId); this.performanceMetrics.delete(tabId); }