Arbitrum MCP Server

Instructions

Implementation Reference

• src/index.ts:740-757 (handler)

  MCP tool handler for 'assertion_status': resolves RPC URL using chainName or rpcUrl, instantiates ArbitrumChainClient, calls getAssertionStatus with parentRpcUrl and rollupAddress, returns JSON stringified status.
  case "assertion_status": { const rpcUrl = await this.resolveRpcUrl( (args.rpcUrl as string) || (args.chainName as string) ); const chainDataClient = new ArbitrumChainClient(rpcUrl); const status = await chainDataClient.getAssertionStatus( args.parentRpcUrl as string, args.rollupAddress as string ); return { content: [ { type: "text", text: JSON.stringify(status, null, 2), }, ], }; }
• src/index.ts:1591-1619 (schema)

  Input schema and tool definition for 'assertion_status', including description, properties for rpcUrl, chainName (optional), parentRpcUrl and rollupAddress (required). Used for both validation and tool listing/registration.
  { name: "assertion_status", description: "Monitor assertion creation and confirmation activity. Tracks NodeCreated vs NodeConfirmed events to understand rollup validation status. Critical for PM and support teams to monitor chain security and finality.", inputSchema: { type: "object" as const, properties: { rpcUrl: { type: "string", description: "The RPC URL of the Arbitrum chain (optional if default is set)", }, chainName: { type: "string", description: "Chain name (e.g., 'Xai', 'Arbitrum One') - will auto-resolve to RPC URL", }, parentRpcUrl: { type: "string", description: "Parent chain RPC URL (e.g., Ethereum mainnet RPC)", }, rollupAddress: { type: "string", description: "Rollup contract address", }, }, required: ["parentRpcUrl", "rollupAddress"], }, },
• src/clients/arbitrum-chain-client.ts:167-245 (helper)

  Core helper function getAssertionStatus that queries recent NodeCreated and NodeConfirmed events from the rollup contract on parent chain to determine latest assertions created/confirmed and the confirmation gap.
  async getAssertionStatus( parentRpcUrl: string, rollupAddress: string ): Promise<AssertionStatus> { try { const parentClient = createPublicClient({ transport: http(parentRpcUrl), }); const nodeCreatedEventAbi = { anonymous: false, inputs: [ { indexed: true, name: "nodeNum", type: "uint64" }, { indexed: true, name: "parentNodeHash", type: "bytes32" }, { indexed: true, name: "nodeHash", type: "bytes32" }, { indexed: false, name: "executionHash", type: "bytes32" }, ], name: "NodeCreated", type: "event", } as const; const nodeConfirmedEventAbi = { anonymous: false, inputs: [ { indexed: true, name: "nodeNum", type: "uint64" }, { indexed: false, name: "blockHash", type: "bytes32" }, { indexed: false, name: "sendRoot", type: "bytes32" }, ], name: "NodeConfirmed", type: "event", } as const; const latestBlockNumber = await parentClient.getBlockNumber(); const fromBlock = latestBlockNumber - BigInt(50000); const [createdLogs, confirmedLogs] = await Promise.all([ parentClient.getLogs({ address: rollupAddress as `0x${string}`, event: nodeCreatedEventAbi, fromBlock, toBlock: latestBlockNumber, }), parentClient.getLogs({ address: rollupAddress as `0x${string}`, event: nodeConfirmedEventAbi, fromBlock, toBlock: latestBlockNumber, }) ]); const latestCreatedAssertion = createdLogs.length > 0 ? createdLogs[createdLogs.length - 1].args?.nodeNum || null : null; const latestConfirmedAssertion = confirmedLogs.length > 0 ? confirmedLogs[confirmedLogs.length - 1].args?.nodeNum || null : null; const creationConfirmationGap = (latestCreatedAssertion && latestConfirmedAssertion) ? latestCreatedAssertion - latestConfirmedAssertion : 0n; const summary = `Latest created assertion: ${latestCreatedAssertion || 'None'}, Latest confirmed: ${latestConfirmedAssertion || 'None'}. Gap: ${creationConfirmationGap}`; return { latestCreatedAssertion: latestCreatedAssertion ? latestCreatedAssertion.toString() : null, latestConfirmedAssertion: latestConfirmedAssertion ? latestConfirmedAssertion.toString() : null, creationConfirmationGap: creationConfirmationGap.toString(), summary }; } catch (error) { return { latestCreatedAssertion: null, latestConfirmedAssertion: null, creationConfirmationGap: "0", summary: `Error checking assertions: ${error instanceof Error ? error.message : 'Unknown error'}` }; } }
• src/clients/arbitrum-chain-client.ts:14-19 (schema)

  TypeScript interface defining the output structure of AssertionStatus returned by getAssertionStatus.
  export interface AssertionStatus { latestCreatedAssertion: string | null; latestConfirmedAssertion: string | null; creationConfirmationGap: string; summary: string; }