MCP Ethers Wallet

Implementation Reference

• src/tools/erc721.ts:399-418 (handler)

  The inline handler function for the approveNFT MCP tool. It invokes the approve helper from the ERC721 service, sends the transaction, and returns success/error messages with transaction hash.
  async ({ contractAddress, tokenId, approved, provider, chainId, gasOptions }) => { try { const tx = await approve(ethersService, contractAddress, approved, tokenId.toString(), provider, chainId, gasOptions); return { content: [{ type: "text", text: `Successfully approved ${approved} to transfer NFT #${tokenId} Transaction Hash: ${tx.hash} Waiting for confirmation...` }] }; } catch (error) { return { isError: true, content: [{ type: "text", text: `Error approving NFT transfer: ${error instanceof Error ? error.message : String(error)}` }] }; }
• src/tools/erc721.ts:391-397 (schema)

  Zod input schema for the approveNFT tool parameters, validating contract address, token ID, approved address, provider, chain ID, and gas options.
  { contractAddress: contractAddressSchema, tokenId: tokenIdSchema, approved: addressSchema, provider: providerSchema, chainId: chainIdSchema, gasOptions: gasOptionsSchema
• src/tools/erc721.ts:389-419 (registration)

  MCP server.tool registration for the approveNFT tool within the registerERC721Tools function. Includes name, schema, description (implicit), and handler.
  server.tool( "approveNFT", { contractAddress: contractAddressSchema, tokenId: tokenIdSchema, approved: addressSchema, provider: providerSchema, chainId: chainIdSchema, gasOptions: gasOptionsSchema }, async ({ contractAddress, tokenId, approved, provider, chainId, gasOptions }) => { try { const tx = await approve(ethersService, contractAddress, approved, tokenId.toString(), provider, chainId, gasOptions); return { content: [{ type: "text", text: `Successfully approved ${approved} to transfer NFT #${tokenId} Transaction Hash: ${tx.hash} Waiting for confirmation...` }] }; } catch (error) { return { isError: true, content: [{ type: "text", text: `Error approving NFT transfer: ${error instanceof Error ? error.message : String(error)}` }] }; } }
• src/services/erc/erc721.ts:631-682 (helper)

  Supporting helper function that performs the actual approve transaction. Includes ownership/approval checks, contract instantiation, transaction overrides, and ethers.Contract.approve call.
  export async function approve( ethersService: EthersService, contractAddress: string, approvedAddress: string, tokenId: string | number, provider?: string, chainId?: number, options: TokenOperationOptions = {} ): Promise<ethers.TransactionResponse> { metrics.incrementCounter('erc721.approve'); return timeAsync('erc721.approve', async () => { try { // Get provider and signer from ethers service const signer = ethersService['getSigner'](provider, chainId); const signerAddress = await signer.getAddress(); // Check ownership const owner = await ownerOf(ethersService, contractAddress, tokenId, provider, chainId); if (owner.toLowerCase() !== signerAddress.toLowerCase()) { // Check if signer is approved for all const isApproved = await isApprovedForAll(ethersService, contractAddress, owner, signerAddress, provider, chainId); if (!isApproved) { throw new UnauthorizedTokenActionError( `Not authorized to approve token #${tokenId}. You are not the owner or approved operator.` ); } } // Create contract instance with signer const contractWithSigner = new ethers.Contract(contractAddress, ERC721_ABI, signer); // Prepare transaction overrides const overrides: ethers.Overrides = {}; if (options.gasLimit) overrides.gasLimit = options.gasLimit; if (options.gasPrice) overrides.gasPrice = options.gasPrice; if (options.maxFeePerGas) overrides.maxFeePerGas = options.maxFeePerGas; if (options.maxPriorityFeePerGas) overrides.maxPriorityFeePerGas = options.maxPriorityFeePerGas; if (options.nonce !== undefined) overrides.nonce = options.nonce; // Send transaction const tx = await contractWithSigner.approve(approvedAddress, tokenId, overrides); return tx; } catch (error) { logger.debug('Error approving address for NFT', { contractAddress, tokenId, approvedAddress, error }); throw handleTokenError(error, 'Failed to approve address for NFT'); } }); }
• src/tools/index.ts:12-25 (registration)

  Top-level registration in tools index: imports and calls registerERC721Tools which registers approveNFT among other ERC721 tools.
  import { registerERC721Tools } from './erc721.js'; import { registerERC1155Tools } from './erc1155.js'; import { registerNetworkTools } from './networkTools.js'; import { registerPromptTools } from './promptTools.js'; import { silentLogger } from "../utils/silentLogger.js"; /** * Registers all tools with the MCP server */ export function registerAllTools(server: McpServer, ethersService: any) { // Register tool categories registerCoreTools(server, ethersService); registerERC20Tools(server, ethersService); registerERC721Tools(server, ethersService);