rpc_call_contract

Execute read-only smart contract functions to query blockchain data without transaction fees. Decodes return values using contract ABI for viewing balances, checking conditions, and reading contract state.

Instructions

Call read-only smart contract function via eth_call (FREE - no gas cost).

EXECUTES: View/pure function on deployed contract DECODES: Return values using provided ABI FREE: No transaction fee, no state changes

USE FOR: Reading contract state, querying balances, checking conditions.

Input Schema

TableJSON Schema

Name	Required	Description
`contractAddress`	Yes	Contract address (0x...)
`abi`	Yes	Contract ABI
`functionName`	Yes	Function to call
`args`	No	Function arguments

Implementation Reference

src/tools/rpc.ts:128-179 (handler)

The main handler function that implements the rpc_call_contract tool. It validates the contract address, calls jsonRpcService.callContract to perform the read-only eth_call, and returns formatted success/error results with metadata.

export async function rpcCallContract(args: {
  contractAddress: string;
  abi: any[];
  functionName: string;
  args?: any[];
  blockNumber?: string;
  network?: 'mainnet' | 'testnet' | 'previewnet' | 'local';
}): Promise<ToolResult> {
  try {
    logger.info('Calling contract function (read-only)', {
      contractAddress: args.contractAddress,
      functionName: args.functionName,
      network: args.network,
    });

    // Validate address
    if (!args.contractAddress.startsWith('0x') || args.contractAddress.length !== 42) {
      throw new Error('Invalid contract address format');
    }

    const result = await jsonRpcService.callContract({
      contractAddress: args.contractAddress,
      abi: args.abi,
      functionName: args.functionName,
      args: args.args,
      blockNumber: args.blockNumber,
      network: args.network,
    });

    return {
      success: true,
      data: {
        functionName: args.functionName,
        result,
      },
      metadata: {
        executedVia: 'json_rpc_relay',
        command: 'contract call (read-only)',
      },
    };
  } catch (error) {
    logger.error('Contract call failed', { error });
    return {
      success: false,
      error: error instanceof Error ? error.message : 'Unknown error occurred',
      metadata: {
        executedVia: 'json_rpc_relay',
        command: 'contract call (read-only)',
      },
    };
  }
}

src/index.ts:250-269 (schema)

The input schema and tool definition for rpc_call_contract used in the optimizedToolDefinitions array for MCP tool listing.

  {
    name: 'rpc_call_contract',
    description: `Call read-only smart contract function via eth_call (FREE - no gas cost).

EXECUTES: View/pure function on deployed contract
DECODES: Return values using provided ABI
FREE: No transaction fee, no state changes

USE FOR: Reading contract state, querying balances, checking conditions.`,
    inputSchema: {
      type: 'object' as const,
      properties: {
        contractAddress: { type: 'string', description: 'Contract address (0x...)' },
        abi: { type: 'array', items: {}, description: 'Contract ABI' },
        functionName: { type: 'string', description: 'Function to call' },
        args: { type: 'array', items: {}, description: 'Function arguments' },
      },
      required: ['contractAddress', 'abi', 'functionName'],
    },
  },

src/index.ts:608-610 (registration)
Tool execution registration in the main switch dispatcher. Maps the tool name to the rpcCallContract handler invocation.
```
case 'rpc_call_contract':
  result = await rpcCallContract(args as any);
  break;
```

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