@hashgraph/hedera-agent-kit-langchain

LangChain integration for Hedera Agent Kit. Wraps Hedera tools as LangChain StructuredTool instances so you can use them with LangChain agents and LangGraph workflows.

Getting started

1. Install dependencies

npm install @hashgraph/hedera-agent-kit-langchain @hashgraph/hedera-agent-kit @hiero-ledger/sdk @langchain/openai dotenv

2. Configure environment variables

Create a .env file:

ACCOUNT_ID=0.0.12345
PRIVATE_KEY=302e...
OPENAI_API_KEY=sk-...

Get your Hedera testnet keys at https://portal.hedera.com/dashboard. We recommend using the DER-encoded private key.

3. Create an agent

import 'dotenv/config';
import { Client, AccountId, PrivateKey } from '@hiero-ledger/sdk';
import { ChatOpenAI } from '@langchain/openai';
import { createAgent } from 'langchain';
import { HederaLangchainToolkit } from '@hashgraph/hedera-agent-kit-langchain';
import {
  coreTokenPlugin,
  coreAccountPlugin,
  coreConsensusPlugin,
} from '@hashgraph/hedera-agent-kit/plugins';
import { AgentMode } from '@hashgraph/hedera-agent-kit';

const client = Client.forTestnet();
client.setOperator(
  AccountId.fromString(process.env.ACCOUNT_ID!),
  PrivateKey.fromStringDer(process.env.PRIVATE_KEY!),
);

const toolkit = new HederaLangchainToolkit({
  client,
  configuration: {
    plugins: [coreTokenPlugin, coreAccountPlugin, coreConsensusPlugin],
    context: { mode: AgentMode.AUTONOMOUS },
  },
});

const agent = createAgent({
  model: new ChatOpenAI({ model: 'gpt-4o' }),
  tools: toolkit.getTools(),
});

const response = await agent.invoke({
  messages: [{ role: 'user', content: 'Create a new Hedera account' }],
});

console.log(response.messages.at(-1)?.content);

Parsing tool responses

Use ResponseParserService to extract structured data from agent responses:

import { ResponseParserService } from '@hashgraph/hedera-agent-kit-langchain';

const parser = new ResponseParserService(toolkit.getTools());
const response = await agent.invoke({ messages: [...] });
const parsed = parser.parseNewToolMessages(response);

console.log(parsed[0].toolName);   // e.g. "create_account_tool"
console.log(parsed[0].parsedData); // tool execution result

MCP server support

The toolkit can also load tools from external MCP servers:

import { HederaMCPServer } from '@hashgraph/hedera-agent-kit-langchain';

const toolkit = new HederaLangchainToolkit({
  client,
  configuration: {
    plugins: [coreTokenPlugin],
    context: { mode: AgentMode.AUTONOMOUS },
    mcpServers: [HederaMCPServer.HEDERION_MCP_MAINNET],
  },
});

const mcpTools = await toolkit.getMcpTools();
const allTools = [...toolkit.getTools(), ...mcpTools];

License

Apache-2.0