@hashgraphonline/hedera-agent-kit/src/langchain/tools/scs/execute-contract-tool.ts

Build LLM-powered applications that interact with the Hedera Network. Create conversational agents that can understand user requests in natural language and execute Hedera transactions, or build backend systems that leverage AI for on-chain operations.

import { z } from 'zod';
import { ExecuteContractParams } from '../../../types';
import {
  BaseHederaTransactionTool,
  BaseHederaTransactionToolParams,
} from '../common/base-hedera-transaction-tool';
import { BaseServiceBuilder } from '../../../builders/base-service-builder';
import { ScsBuilder } from '../../../builders/scs/scs-builder';

const FunctionParameterInputSchema = z.object({
  type: z
    .string()
    .describe(
      'Parameter type (e.g., string, bytes, bytes32, bool, int8, int32, int64, int256, uint8, uint32, uint64, uint256, address).'
    ),
  value: z
    .any()
    .describe(
      'Parameter value. For bytes/bytes32, use hex string. For address, use "0.0.xxxx" string.'
    ),
});

const ExecuteContractZodSchemaCore = z.object({
  contractId: z
    .string()
    .describe('The ID of the contract to call (e.g., "0.0.xxxx").'),
  gas: z
    .union([z.number(), z.string()])
    .describe('Gas to use for the call. Builder handles Long conversion.'),
  functionName: z
    .string()
    .describe(
      'The function to call (e.g., "myFunction" or "myFunction(uint32)").'
    ),
  functionParameters: z
    .array(FunctionParameterInputSchema)
    .optional()
    .describe(
      'Optional. Array of function parameters, each with type and value. Builder parses and constructs.'
    ),
  payableAmount: z
    .union([z.number(), z.string()])
    .optional()
    .describe(
      'Optional. Amount in HBAR to send. Builder handles Hbar unit conversion.'
    ),
  memo: z.string().optional().describe('Optional. Memo for the transaction.'),
});

export class HederaExecuteContractTool extends BaseHederaTransactionTool<
  typeof ExecuteContractZodSchemaCore
> {
  name = 'hedera-scs-execute-contract';
  description =
    'Executes a smart contract function. Builder handles parameter parsing, type conversions, and Hbar unit logic.';
  specificInputSchema = ExecuteContractZodSchemaCore;
  namespace = 'scs';

  constructor(params: BaseHederaTransactionToolParams) {
    super(params);
  }

  protected getServiceBuilder(): BaseServiceBuilder {
    return this.hederaKit.scs();
  }

  protected async callBuilderMethod(
    builder: BaseServiceBuilder,
    specificArgs: z.infer<typeof ExecuteContractZodSchemaCore>
  ): Promise<void> {
    await (builder as ScsBuilder).executeContract(
      specificArgs as unknown as ExecuteContractParams
    );
  }
}