SDK Quickstart

Use the @abstraxn/agent-kit npm package from your backend only. It wraps Agent Kit REST and Abstraxn server wallet provisioning so each agent gets an EVM (and optionally Solana) address plus a one-time access key for signing. For bring-your-own-wallet (MetaMask, viem, no accessKey), see External wallet.

Prerequisites

Node.js 18+
Application API key from Dashboard → Agentic Stack → Overview
A backend database (Postgres, etc.) to store per-agent secrets

Install

npm install @abstraxn/agent-kit

Initialize the client

import { AgentKitClient } from '@abstraxn/agent-kit';

const agentKit = new AgentKitClient({
  apiKey: process.env.ABSTRAXN_API_KEY!, // same key as dashboard Overview
  baseUrl: process.env.AGENT_KIT_BASE_URL, // optional; default production host
});

Env variable	Example	Purpose
`ABSTRAXN_API_KEY`	From dashboard Overview	Application-scoped key
`AGENT_KIT_BASE_URL`	`https://dev-agent-kit.abstraxn.com`	Override for dev/staging

Create an agent (primary flow)

createAgent() is the flow used in the sample backend API (NestJS). It:

Registers the agent in Agent Kit (POST /agents under the hood).
Provisions an Abstraxn server wallet (P-256 access key + organization).
Returns wallet.accessKey — required for all future signing and autonomous actions.

const { agent, wallet } = await agentKit.createAgent({
  name: 'Trading Assistant',
  description: 'Executes trades within spend policy',
  userIdentity: 'user-123@example.com', // your stable user id
  userEmail: 'user@example.com',       // optional
  metadata: { tier: 'pro' },             // optional
});

// Agent Kit record
console.log(agent.id);        // UUID — use in MCP agent_id when needed
console.log(agent.apiKey);    // per-agent MCP/REST key (optional second credential)

// Wallet — persist on YOUR backend
console.log(wallet.evmAddress);
console.log(wallet.solanaAddress);   // when enabled
console.log(wallet.organizationId);
console.log(wallet.accessKey);       // ⚠️ shown once — encrypt at rest

What to store in your database

Field	Secret?	Used for
`agent.id`	No	Agent Kit id, MCP `agent_id`, identity APIs
`agent.apiKey`	Yes	Per-agent MCP auth (alternative to app key + `agent_id`)
`wallet.accessKey`	Critical	Server wallet auth — signing, x402, transfers
`wallet.evmAddress`	No	Display, balance, transfers
`wallet.organizationId`	No	Server signer RPC client scope
`userIdentity`	No	Must match `authenticate()` calls

accessKey cannot be retrieved again. If you lose it, create a new agent or implement a key-rotation flow with your Abstraxn contact. Encrypt the column (see ENCRYPTION_KEY in the sample app).

Reference: how the sample backend persists secrets

import { encrypt } from './common/crypto.helper';

const accessKeyEncrypted = encrypt(wallet.accessKey, process.env.ENCRYPTION_KEY!);

await agentsRepo.save({
  userId,
  agentId: kitAgent.id,
  apiKey: kitAgent.apiKey,
  evmAddress: wallet.evmAddress,
  organizationId: wallet.organizationId,
  userIdentity: kitAgent.userIdentity ?? userId,
  accessKey: accessKeyEncrypted, // never return in API responses
});

Sign and send transactions (autonomous actions)

After onboarding, load the decrypted accessKey and use getServerSigner():

const signer = agentKit.getServerSigner();

await signer.authenticate({
  userIdentity: storedUserIdentity,
  accessKey: decryptedAccessKey,
});

const client = signer.createPublicClient({
  rpcUrl: process.env.RPC_URL!,
  chainId: 80002,
  organizationId: storedOrganizationId,
  fromAddress: storedEvmAddress as `0x${string}`,
});

const prepared = await client.prepareTransaction({
  to: '0xRecipient...' as `0x${string}`,
  value: 1_000_000_000_000_000n,
});

const txHash = await client.signAndSendPreparedTransaction(
  prepared.unsignedTransaction,
);

Your backend uses this path when:

Auto-signing MCP transfer unsigned transactions (see Full-stack app integration).
Building x402 paymentPayload for paid_fetch retries (see x402 payments).

Other SDK methods

Method	When to use
`listAgents` / `getAgent`	Admin dashboards, sync with your DB
`updateAgent` / `deleteAgent`	Lifecycle management
`updateSpendPolicy`	Cap paid MCP tool spend per agent (x402)
`createInteractionPolicy` / `listInteractionPolicies` / `getInteractionPolicy` / `updateInteractionPolicy` / `deleteInteractionPolicy`	Off-chain guardrails before MCP tool calls (interaction policies)
`registerAgentIdentity`	ERC-8004 on-chain identity — supported `chainId`: `1`, `11155111`, `137`, `80002`, `8453`, `84532`, `56`, `97`, `42161`, `43114` (details)
`createAgentDirect`	Agent row only, no auto-wallet (advanced)
`bindAgent`	Attach existing EVM/Solana addresses

MCP from your backend

Point MCP at the same URL as the dashboard MCP URL:

export MCP_SERVER_URL="https://agent-kit.abstraxn.com/mcp"
export MCP_SERVER_AUTH_TOKEN="$ABSTRAXN_API_KEY"

When using the application API key, pass agent_id in tool arguments for multi-agent apps:

{
  "name": "get_balance",
  "arguments": {
    "agent_id": "<agent.id from createAgent>",
    "chain": "ethereum"
  }
}

Or use each agent’s agent.apiKey as the MCP Authorization value (no agent_id required).

Security checklist

Store ABSTRAXN_API_KEY and all accessKey values only on the server.
Encrypt accessKey at rest; never log it.
Do not pass accessKey to the browser or mobile clients.
Use per-user auth (JWT) in your API; map users to agent rows in your DB.

Next steps

Interaction policies — contract/recipient/amount guardrails per agent
MCP tools reference — what each tool returns
x402 payments — paid_fetch and payment signing
ERC-8004 agent identity — on-chain registration + dashboard Identity tab
Full-stack app integration — sample NestJS API + Next.js app with chat + MCP

Getting started

SDK & wallets

Third-party integrations

Off-chain policies

Identity

Build your app

MCP

Payments

Help

Prerequisites

Install

Initialize the client

Create an agent (primary flow)

What to store in your database

Reference: how the sample backend persists secrets

Sign and send transactions (autonomous actions)

Other SDK methods

MCP from your backend

Security checklist

Next steps

​Prerequisites

​Install

​Initialize the client

​Create an agent (primary flow)

​What to store in your database

​Reference: how the sample backend persists secrets

​Sign and send transactions (autonomous actions)

​Other SDK methods

​MCP from your backend

​Security checklist

​Next steps

Prerequisites

Install

Initialize the client

Create an agent (primary flow)

What to store in your database

Reference: how the sample backend persists secrets

Sign and send transactions (autonomous actions)

Other SDK methods

MCP from your backend

Security checklist

Next steps