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AgentPay x402 — Crypto Data Tools for AI Agents

by romudille-bit
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Python
Remote

AgentPay — your agent is only as smart as its data.

AgentPay is an open x402 payment gateway that lets AI agents autonomously access real crypto data tools using USDC on Stellar or Base.

No subscriptions. No API keys. No human in the loop. Agents discover tools, pay per call ($0.001–$0.005), and get real data back — all within a hard budget cap.

→ 12 live tools: token prices, whale activity, gas tracker, DeFi TVL, Fear & Greed, yield scanner, funding rates, token security, Dune queries and more → Budget-aware Session: agents estimate costs, track spend, never exceed budget → x402 protocol: works with any x402-compatible agent → Stellar + Base: pay with USDC on either network — Stellar (5s, $0.00001 fee) or Base mainnet (2s, $0.0001 fee)

Try it in 60 seconds:

curl https://gateway-production-2cc2.up.railway.app/faucet

Or open the browser faucet: https://gateway-production-2cc2.up.railway.app/faucet/ui

Live gateway: https://gateway-production-2cc2.up.railway.app

Quickstart — 3 steps

Step 1: Get a funded test wallet

One call gives you a ready-to-use Stellar testnet wallet with 5 USDC pre-loaded:

curl https://gateway-production-2cc2.up.railway.app/faucet

Or use the browser faucet — click "Get Test Wallet", copy the snippet, run it.

Step 2: Create a Session with a budget

from agent.wallet import AgentWallet, Session, BudgetExceeded

wallet = AgentWallet(
    secret_key="S...",       # your Stellar secret key
    network="testnet",       # or "mainnet"
)

GATEWAY = "https://gateway-production-2cc2.up.railway.app"

with Session(wallet=wallet, gateway_url=GATEWAY, max_spend="0.05") as session:
    print(f"Balance:  {wallet.get_usdc_balance()} USDC")
    print(f"Budget:   {session.remaining()} remaining")

The Session enforces a hard USDC cap across all calls. It raises BudgetExceeded before any payment goes out if a tool would push you over, and automatically falls back to the next-cheapest tool in the same category when the preferred one is too expensive.

Step 3: Call tools — payment is automatic

with Session(wallet=wallet, gateway_url=GATEWAY, max_spend="0.05") as session:

    # Token price — $0.001
    r = session.call("token_price", {"symbol": "ETH"})
    print(f"ETH: ${r['price_usd']:,.2f}  ({r['change_24h_pct']:+.2f}% 24h)")

    # Fear & Greed Index — $0.001
    r = session.call("fear_greed_index", {"limit": 1})
    print(f"Sentiment: {r['value']}/100 — {r['value_classification']}")

    # DeFi TVL — $0.002
    r = session.call("defi_tvl", {"protocol": "aave"})
    print(f"Aave TVL: ${r['tvl'] / 1e9:.1f}B  ({r['change_1d']:+.1f}% 24h)")

    # Crypto news — $0.003
    r = session.call("crypto_news", {"currencies": "ETH", "filter": "hot"})
    for h in r["headlines"][:3]:
        print(f"  [{h['sentiment']:>7}] {h['title'][:55]}")

    print(f"\nTotal spent: {session.spent()}")
    print(f"Remaining:   {session.remaining()}")

Each session.call() handles the full x402 flow internally:

  1. Checks your remaining budget against the tool's price (pre-flight, no payment yet)

  2. POSTs to the gateway, receives a 402 with {payment_id, amount_usdc, pay_to}

  3. Sends USDC on Stellar — ~2–3 seconds on testnet

  4. Retries the request with X-Payment: tx_hash=<hash>,from=<addr>,id=<payment_id>

  5. Returns the data

Available Tools

Tool

Price

Parameters

Returns

token_price

$0.001

symbol (BTC, ETH, SOL…)

price_usd, change_24h_pct, market_cap_usd

gas_tracker

$0.001

—

slow/standard/fast gwei, base_fee_gwei

fear_greed_index

$0.001

limit (days of history, default 1)

value 0–100, value_classification, history[ ]

wallet_balance

$0.002

address, chain (ethereum/stellar)

token balances

whale_activity

$0.002

token, min_usd (default 100k)

large_transfers[ ], total_volume_usd

defi_tvl

$0.002

protocol (optional, e.g. "uniswap")

tvl, change_1d, change_7d, chains[ ]

token_security

$0.002

contract_address, chain (ethereum/bsc)

risk_level, is_honeypot, buy_tax, sell_tax, holder_count

yield_scanner

$0.004

token, chain (optional), min_tvl (default $1M)

top 10 pools by APY with protocol, tvl_usd, risk_level

dex_liquidity

$0.003

token_a, token_b

volume_24h_usd, market_cap_usd, ath_usd

funding_rates

$0.003

asset (optional, e.g. "BTC")

funding_rate_pct, annualized_rate_pct, sentiment per exchange

crypto_news

$0.003

currencies (e.g. "ETH,BTC"), filter (hot/new/rising)

headlines[ ] with title, url, sentiment, score

dune_query

$0.005

query_id, limit (default 25)

rows[ ], columns[ ], row_count from Dune Analytics

Discover all tools dynamically:

import httpx
tools = httpx.get(f"{GATEWAY}/tools").json()["tools"]
for t in tools:
    print(f"{t['name']:<22} ${t['price_usdc']}  — {t['description']}")

Payment Options

AgentPay accepts USDC payments on two networks:

  • Stellar — $0.00001 per tx, 5-second settlement (recommended for agents using the Python SDK)

  • Base — $0.0001 per tx, 2-second settlement (EIP-3009 transferWithAuthorization on Base mainnet)

The gateway's 402 response advertises both options simultaneously. Clients pick the network that suits them — no configuration required on the tool side.

{
  "payment_options": {
    "stellar": { "pay_to": "G...", "amount_usdc": "0.001", ... },
    "base":    { "network": "eip155:8453", "asset": "0x833589f...", "amount_usdc": "0.001", ... }
  }
}

Base payments use Mode B direct on-chain settlement: the client calls transferWithAuthorization on the USDC contract and sends the tx_hash in the PAYMENT-SIGNATURE header. The gateway verifies the receipt via JSON-RPC.

MCP Server

AgentPay ships a Model Context Protocol server that gives Claude Desktop direct access to all 12 tools. Payments happen automatically in the background using Stellar USDC.

See README_MCP.md for setup instructions.

Quick config (claude_desktop_config.json):

{
  "mcpServers": {
    "agentpay": {
      "command": "python",
      "args": ["/path/to/agentpay/gateway/mcp_server.py"],
      "env": {
        "STELLAR_SECRET_KEY": "S...",
        "AGENTPAY_GATEWAY_URL": "https://gateway-production-2cc2.up.railway.app"
      }
    }
  }
}

Without the SDK — raw HTTP

The x402 flow works with any HTTP client in any language.

GATEWAY="https://gateway-production-2cc2.up.railway.app"
AGENT_ADDR="G..."   # your Stellar public key

# 1. Call the tool → receive 402 payment challenge
RESPONSE=$(curl -s -X POST "$GATEWAY/tools/token_price/call" \
  -H "Content-Type: application/json" \
  -d "{\"parameters\":{\"symbol\":\"ETH\"},\"agent_address\":\"$AGENT_ADDR\"}")

PAYMENT_ID=$(echo $RESPONSE | python3 -c "import sys,json; print(json.load(sys.stdin)['payment_id'])")
AMOUNT=$(echo $RESPONSE    | python3 -c "import sys,json; print(json.load(sys.stdin)['amount_usdc'])")
PAY_TO=$(echo $RESPONSE    | python3 -c "import sys,json; print(json.load(sys.stdin)['pay_to'])")

# 2. Send USDC on Stellar (memo = first 28 chars of payment_id)
TX_HASH=$(python3 -c "
from stellar_sdk import Keypair, Server, Network, Asset, TransactionBuilder
kp = Keypair.from_secret('S...')
server = Server('https://horizon-testnet.stellar.org')
acct = server.load_account(kp.public_key)
tx = (TransactionBuilder(acct, Network.TESTNET_NETWORK_PASSPHRASE, base_fee=100)
      .add_text_memo('$PAYMENT_ID'[:28])
      .append_payment_op('$PAY_TO', Asset('USDC','GBBD47IF6LWK7P7MDEVSCWR7DPUWV3NY3DTQEVFL4NAT4AQH3ZLLFLA5'), '$AMOUNT')
      .set_timeout(30).build())
tx.sign(kp)
print(server.submit_transaction(tx)['hash'])
")

# 3. Retry with payment proof → get data
curl -s -X POST "$GATEWAY/tools/token_price/call" \
  -H "Content-Type: application/json" \
  -H "X-Payment: tx_hash=$TX_HASH,from=$AGENT_ADDR,id=$PAYMENT_ID" \
  -d "{\"parameters\":{\"symbol\":\"ETH\"},\"agent_address\":\"$AGENT_ADDR\"}"

Session API reference

# Pre-check price without paying
price = session.estimate("dune_query")       # "$0.005"

# Check headroom before committing
if not session.would_exceed("0.005"):
    result = session.call("dune_query", {"query_id": 3810512, "limit": 10})

# Access spend state mid-session
session.spent()        # "$0.004"
session.remaining()    # "$0.046"

# Full breakdown after session closes
summary = session.summary()
# {
#   "calls": 3,
#   "spent_usdc": "0.006",
#   "spent_fmt": "$0.006",
#   "remaining_fmt": "$0.044",
#   "breakdown": [
#     {"tool": "token_price", "amount_usdc": "0.001", "tx_hash": "abc123..."},
#     {"tool": "gas_tracker",  "amount_usdc": "0.001", "tx_hash": "def456..."},
#     {"tool": "defi_tvl",     "amount_usdc": "0.002", "tx_hash": "ghi789..."}
#   ]
# }

Run the demo

git clone <this-repo> && cd agentpay
python -m venv venv && source venv/bin/activate
pip install -r requirements.txt

# Copy env and add your Stellar secret key
cp .env.example .env

# Run the full 5-tool ETH analysis against the live gateway
AGENTPAY_GATEWAY_URL=https://gateway-production-2cc2.up.railway.app \
  python agent/budget_demo.py

Expected output: ETH price, gas, DEX liquidity, whale moves, and Dune onchain data — all paid for autonomously in ~$0.012 USDC.

Architecture

agent (Python SDK)
    │
    │  POST /tools/{name}/call
    │  ← 402 {payment_options: {stellar: {...}, base: {...}}}
    │  → Stellar USDC payment (~3s)  OR  Base transferWithAuthorization (~2s)
    │  → retry with X-Payment or PAYMENT-SIGNATURE header
    │  ← 200 {result: ...}
    ▼
gateway (FastAPI on Railway)
    │
    ├── registry/registry.py   — 12-tool catalog with prices & dev wallets
    ├── gateway/stellar.py     — Stellar payment verification via Horizon
    ├── gateway/base.py        — Base payment verification via JSON-RPC
    └── gateway/main.py        — real API dispatchers
            ├── CoinGecko      token_price, dex_liquidity
            ├── Etherscan V2   gas_tracker, whale_activity, wallet_balance
            ├── DeFiLlama      defi_tvl
            ├── alternative.me fear_greed_index
            ├── Reddit         crypto_news
            ├── Dune Analytics dune_query
            ├── GoPlus         token_security
            ├── DeFiLlama      yield_scanner
            └── Binance/Bybit/OKX funding_rates

Fee model: Gateway charges 15% (GATEWAY_FEE_PERCENT=0.15), forwards the rest to each tool developer's Stellar wallet. All payments settle on-chain in ~2–5 seconds.

Note: AgentPay currently uses the x402 pay-first pattern with classic Stellar PAYMENT ops. OZ Facilitator (verify-first, Soroban SAC) migration planned for v2.

Agent Discovery

AgentPay is discoverable by autonomous agents at standard discovery paths:

  • AgentPay manifest: https://gateway-production-2cc2.up.railway.app/.well-known/agentpay.json

  • A2A agent card: https://gateway-production-2cc2.up.railway.app/.well-known/agent.json

Any x402-compatible agent can discover and use AgentPay tools without human setup.

All 12 AgentPay tools are also indexed on x402scout under network: stellar-testnet.

Install Server
A
security – no known vulnerabilities
F
license - not found
-
quality - not tested

How are these scores calculated?

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