Arbitrum MCP Server

Instructions

Implementation Reference

• src/index.ts:170-184 (handler)

  Main MCP tool handler for 'sync_status': resolves RPC URL or chain name, instantiates NitroNodeClient, fetches sync status via getSyncStatus(), and returns JSON-formatted result.
  case "sync_status": { const rpcUrl = await this.resolveRpcUrl( (args.rpcUrl as string) || (args.chainName as string) ); const nodeClient = new NitroNodeClient(rpcUrl); const syncStatus = await nodeClient.getSyncStatus(); return { content: [ { type: "text", text: JSON.stringify(syncStatus, null, 2), }, ], }; }
• src/index.ts:876-890 (schema)

  Tool schema definition in getAvailableTools(): defines name, description, and inputSchema (optional rpcUrl) for the 'sync_status' tool returned by list tools endpoint.
  name: "sync_status", description: "Get node synchronization status (may fall back to current block number if sync API unavailable)", inputSchema: { type: "object" as const, properties: { rpcUrl: { type: "string", description: "The RPC URL of the Arbitrum node (optional if default is set)", }, }, required: [], }, },
• src/index.ts:93-102 (registration)

  MCP server registration for list tools: handles ListToolsRequestSchema by returning all available tools including 'sync_status' from getAvailableTools().
  this.server.setRequestHandler(ListToolsRequestSchema, async () => { try { console.error("Handling list tools request"); return { tools: this.getAvailableTools(), }; } catch (error) { console.error("Error in list tools handler:", error); throw error; }
• src/clients/nitro-node-client.ts:87-134 (helper)

  Core helper method implementing sync status logic: calls eth_syncing and eth_blockNumber RPC methods, computes progress, with fallback to current block if unsupported.
  async getSyncStatus(): Promise<SyncStatus> { try { const syncResponse = await this.makeRpcCall("eth_syncing", []); const latestBlock = await this.makeRpcCall("eth_blockNumber", []); if (syncResponse === false) { return { currentBlock: parseInt(latestBlock, 16), highestBlock: parseInt(latestBlock, 16), isSyncing: false, syncProgress: 100, }; } const current = parseInt(syncResponse.currentBlock, 16); const highest = parseInt(syncResponse.highestBlock, 16); return { currentBlock: current, highestBlock: highest, isSyncing: true, syncProgress: highest > 0 ? (current / highest) * 100 : 0, }; } catch (error) { // Try to get at least the current block number as a fallback try { const latestBlock = await this.makeRpcCall("eth_blockNumber", []); const blockNum = parseInt(latestBlock, 16); return { currentBlock: blockNum, highestBlock: blockNum, isSyncing: false, syncProgress: 100, error: "Sync status not supported on this RPC endpoint. Showing current block number only.", }; } catch (blockError) { return { currentBlock: 0, highestBlock: 0, isSyncing: false, syncProgress: 0, error: "Sync status not supported on this RPC endpoint. This method typically requires access to a node's debug API.", }; } } }
• src/clients/nitro-node-client.ts:9-15 (schema)

  TypeScript interface defining the SyncStatus response structure used by getSyncStatus() and returned by the tool.
  export interface SyncStatus { currentBlock: number; highestBlock: number; isSyncing: boolean; syncProgress: number; error?: string; }