---
id: build/nova-tools-for-agents
title: "Using Nova Tools with AI Agents"
description: "Nova's tools are available to AI agents via the Model Context Protocol (MCP) and a standard REST API with x402 inline payments on Stacks mainnet."
product: nova
canonical: https://zeroauthoritydao.ai/docs/build/nova-tools-for-agents
related: [build]
tokens: 806
---

# Using Nova Tools with AI Agents

Explains how AI agents connect to Nova Tools over MCP or REST, discover tools, which callers pay per call with x402, and the rate limits for identified and anonymous agents.

> [!NOTE]
> No API keys, no subscriptions, no registration. Free tools run subject to rate limits; paid tools are paid per request via x402 — see the [x402 Payment Guide](https://zeroauthoritydao.ai/docs/build/x402.md) for payment mechanics, accepted tokens, and safety guarantees.

---

## Connecting

### Option 1: MCP Server (Recommended)

Install the Nova MCP server to give your agent native tool access:

```bash
npx @nova/mcp-server
```

Or connect directly via Streamable HTTP:

```
https://nova.zeroauthoritydao.com/mcp
```

**Environment variables** (optional):

| Variable | Default | Description |
|----------|---------|-------------|
| `NOVA_API_URL` | `https://nova.zeroauthoritydao.com` | Nova API base URL |
| `AGENT_STACKS_ADDRESS` | — | Your Stacks address, sent as identity for the higher agent rate limits |

### Option 2: REST API (Direct)

Call tool endpoints directly with standard HTTP:

```bash
curl -X POST https://nova.zeroauthoritydao.com/api/tools/stacks-token-analytics/run \
  -H "Content-Type: application/json" \
  -d '{"input": {"token": "WELSH"}}'
```

Paid tools return **HTTP 402** with payment requirements — the [x402 Payment Guide](https://zeroauthoritydao.ai/docs/build/x402.md) covers how to complete payment and retry.

---

## Tool Discovery

The full catalog (50+ tools across Stacks, Bitcoin, EVM, Solana, TON, Sui, Aptos, Hyperliquid, and community ecosystems) is in the [Tools catalog](https://zeroauthoritydao.ai/docs/nova/tools.md). Machine-readable listings:

| Endpoint | What it returns |
|----------|-----------------|
| `GET /api/tools` | Tool list with slugs, input schemas, and pricing |
| `GET /.well-known/agent.json` | Agent manifest: tools, schemas, payment options, MCP endpoint info |
| `GET /api/tools/openapi.json` | OpenAPI spec |
| `GET /llms.txt` | llms.txt index |

Over MCP, call `tools/list` — every tool is auto-discovered with full input schemas and pricing.

---

## Payment Model

| Caller Type | Paid Tools | Free Tools |
|-------------|-----------|------------|
| **Nova Premium** (JWT) | Free within the monthly included-calls limit | Free, unlimited |
| **Identified agent** (Stacks address) | x402 payment per call | Free, rate-limited |
| **Anonymous** (IP only) | x402 payment per call | Free, stricter rate limits |

Payment mechanics — headers, the 402 flow, accepted tokens, errors, and the verify → execute → settle safety guarantee — live in the [x402 Payment Guide](https://zeroauthoritydao.ai/docs/build/x402.md).

---

## Rate Limits

| Caller Type | Limit |
|-------------|-------|
| Identified agent (x402 / wallet-identified) | **10 req/min, 240 req/hour** |
| Anonymous (per IP) | **5 req/min, 120 req/hour** |

Exceeding limits returns **429 Too Many Requests** (never 402). Include your Stacks address (`AGENT_STACKS_ADDRESS` / `X-STACKS-ADDRESS`) to get the higher agent limits.

---

## Example: Full Agent Flow

1. **Discover tools**: `GET /.well-known/agent.json`
2. **Call a tool**: `POST /api/tools/stacks-token-analytics/run` with `{"input": {"token": "WELSH"}}`
3. **Receive 402**: parse the `payment-required` header for payment options
4. **Sign payment** and **retry** with the `payment-signature` header ([details](https://zeroauthoritydao.ai/docs/build/x402.md))
5. **Receive results**: tool output in the body, settlement receipt in the `payment-response` header