AgentWallet MCP Server

Instructions

Implementation Reference

• src/index.ts:880-912 (registration)

  Tool registration for 'get_token_info' - registers the tool with MCP server, defines the schema using zod, and provides the handler function

  server.tool(
    'get_token_info',
    'Get the name, symbol, and decimals of any ERC-20 token by its contract address. ' +
      'Useful for discovering token details before transfers or approvals.',
    {
      token: z.string().regex(/^0x[a-fA-F0-9]{40}$/).describe('ERC-20 token contract address'),
      chain_id: z.number().int().describe('Chain ID'),
    },
    async ({ token, chain_id }) => {
      if (isSolanaChain(chain_id)) {
        throw new Error('get_token_info is not supported on Solana. Use Solana token metadata programs to query SPL token details.');
      }
      // Make 3 parallel eth_call requests: name(), symbol(), decimals()
      const [nameResult, symbolResult, decimalsResult] = await Promise.all([
        api('/eth-call', 'POST', { chain_id, to: token, data: '0x06fdde03' }).catch(() => ({ result: '0x' })),
        api('/eth-call', 'POST', { chain_id, to: token, data: '0x95d89b41' }).catch(() => ({ result: '0x' })),
        api('/eth-call', 'POST', { chain_id, to: token, data: '0x313ce567' }).catch(() => ({ result: '0x' })),
      ]) as { result: string }[];
  
      const name = decodeAbiString(nameResult.result);
      const symbol = decodeAbiString(symbolResult.result);
      const decimalsHex = decimalsResult.result.replace('0x', '');
      const decimals = decimalsHex ? parseInt(decimalsHex, 16) : 0;
  
      return jsonResponse({
        token,
        chain_id,
        name: name || 'Unknown',
        symbol: symbol || 'Unknown',
        decimals,
      });
    },
  );

• src/index.ts:888-911 (handler)

  Handler function for get_token_info - validates chain is not Solana, makes 3 parallel eth_call requests for name(), symbol(), decimals(), decodes results and returns token metadata

  async ({ token, chain_id }) => {
    if (isSolanaChain(chain_id)) {
      throw new Error('get_token_info is not supported on Solana. Use Solana token metadata programs to query SPL token details.');
    }
    // Make 3 parallel eth_call requests: name(), symbol(), decimals()
    const [nameResult, symbolResult, decimalsResult] = await Promise.all([
      api('/eth-call', 'POST', { chain_id, to: token, data: '0x06fdde03' }).catch(() => ({ result: '0x' })),
      api('/eth-call', 'POST', { chain_id, to: token, data: '0x95d89b41' }).catch(() => ({ result: '0x' })),
      api('/eth-call', 'POST', { chain_id, to: token, data: '0x313ce567' }).catch(() => ({ result: '0x' })),
    ]) as { result: string }[];
  
    const name = decodeAbiString(nameResult.result);
    const symbol = decodeAbiString(symbolResult.result);
    const decimalsHex = decimalsResult.result.replace('0x', '');
    const decimals = decimalsHex ? parseInt(decimalsHex, 16) : 0;
  
    return jsonResponse({
      token,
      chain_id,
      name: name || 'Unknown',
      symbol: symbol || 'Unknown',
      decimals,
    });
  },

• src/index.ts:884-887 (schema)

  Input schema for get_token_info using zod - requires 'token' (0x-prefixed 40-char hex address) and 'chain_id' (integer)

  {
    token: z.string().regex(/^0x[a-fA-F0-9]{40}$/).describe('ERC-20 token contract address'),
    chain_id: z.number().int().describe('Chain ID'),
  },

• src/index.ts:856-878 (helper)

  Helper function decodeAbiString() - decodes ABI-encoded string return values from hex, handles malformed data gracefully, used to decode token name and symbol from eth_call results

  /**
   * Decode an ABI-encoded string return value from hex.
   * Handles malformed data gracefully — returns empty string on any parsing failure.
   */
  function decodeAbiString(hex: string): string {
    try {
      const clean = hex.replace('0x', '');
      if (clean.length < 128) return ''; // offset + length minimum
      // First 32 bytes = offset, next 32 bytes at that offset = length
      const offset = parseInt(clean.slice(0, 64), 16) * 2;
      if (isNaN(offset) || offset + 64 > clean.length) return '';
      const length = parseInt(clean.slice(offset, offset + 64), 16);
      if (isNaN(length) || length === 0) return '';
      const dataHex = clean.slice(offset + 64, offset + 64 + length * 2);
      const pairs = dataHex.match(/.{2}/g);
      if (!pairs) return '';
      // Convert hex to UTF-8
      const bytes = new Uint8Array(pairs.map(b => parseInt(b, 16)));
      return new TextDecoder().decode(bytes);
    } catch {
      return '';
    }
  }