Hello3DMCP Server

Instructions

Implementation Reference

• server.js:1710-1757 (registration)

  Registration of the 'get_camera_distance' tool with the MCP server, including title, description, input schema, and handler function
  mcpServer.registerTool( 'get_camera_distance', { title: 'Get Camera Distance', description: 'Get the current camera distance from origin (dolly position). ' + 'Query this before relative distance changes to ensure accuracy. ' + 'For absolute changes, you may use recently queried state from context if no manual interactions occurred.', inputSchema: {} }, async () => { const sessionId = getCurrentSessionId(); if (!sessionId) { return { content: [ { type: 'text', text: 'Error: No active session found.' } ], isError: true }; } try { const { state, metadata } = await getState(sessionId); const distance = state.camera?.distance ?? 0; return { content: [ { type: 'text', text: formatStateResponse(distance.toString(), 'Camera distance', sessionId, metadata) } ] }; } catch (error) { return { content: [ { type: 'text', text: `Error retrieving camera distance: ${error.message}` } ], isError: true }; } } );
• server.js:1719-1756 (handler)

  Handler function for get_camera_distance tool - retrieves current camera distance from browser state via WebSocket communication and returns formatted response with metadata
  async () => { const sessionId = getCurrentSessionId(); if (!sessionId) { return { content: [ { type: 'text', text: 'Error: No active session found.' } ], isError: true }; } try { const { state, metadata } = await getState(sessionId); const distance = state.camera?.distance ?? 0; return { content: [ { type: 'text', text: formatStateResponse(distance.toString(), 'Camera distance', sessionId, metadata) } ] }; } catch (error) { return { content: [ { type: 'text', text: `Error retrieving camera distance: ${error.message}` } ], isError: true }; } }
• server.js:284-316 (helper)

  Helper function getState() - queries state from browser via WebSocket with timeout handling, returns state with metadata (source, timestamp, cache status)
  async function getState(sessionId) { let state; let source; let wasCached = false; // Always query browser for current state try { state = await queryStateFromBrowser(sessionId); source = 'fresh'; } catch (error) { // If query fails, fall back to cache if available (browser may be disconnected) const cached = sessionStateCache.get(sessionId); if (cached) { console.warn(`Browser query failed for session ${sessionId}, returning cached state: ${error.message}`); state = cached.state; source = 'cache'; wasCached = true; } else { // No cache available, throw error throw new Error(`Unable to retrieve state: ${error.message}. Browser may be disconnected.`); } } // Return state with metadata return { state, metadata: { source, wasCached, timestamp: new Date().toISOString() } }; }
• server.js:319-327 (helper)

  Helper function formatStateResponse() - formats state query responses with property name, session ID, and metadata including staleness warnings
  function formatStateResponse(value, propertyName, sessionId, metadata) { const timestamp = metadata.timestamp; const source = metadata.source; const stalenessWarning = metadata.wasCached ? ' (using cached state - browser may be disconnected)' : ''; return `${propertyName}: ${value} (queried at ${timestamp}, source: ${source}${stalenessWarning})`; }
• server.js:2882-2888 (helper)

  Helper function getCurrentSessionId() - retrieves the current session ID from either STDIO mode or HTTP mode context
  function getCurrentSessionId() { if (isStdioMode) { return STDIO_SESSION_ID; } else { return sessionContext.getStore(); } }