x402 Bazaar Skill

The x402 Bazaar is the discovery layer for the x402 ecosystem — a machine-readable catalog helping AI agents find and integrate with x402-compatible API endpoints and MCP tools. Query, find, pay, and use with no pre-baked integrations.

Two modes:

• Browse only — no wallet needed, zero cost, discover all available services
• Browse + Pay — requires Base wallet with USDC to call discovered endpoints

Prerequisites

Browse only (no keys needed)

python3 agent.py "list services"
python3 agent.py "find weather APIs"

To call paid endpoints

1. Get a Base wallet private key (MetaMask → export, or Coinbase Wallet)
2. Fund with USDC on Base — get from coinbase.com or bridge.base.org
3. Add to .env:

EVM_PRIVATE_KEY="0xYourPrivateKeyHere"
MAX_SPEND_PER_CALL=0.10

Install dependencies (run once)

pip install -r ~/clawd/skills/x402-bazaar/requirements.txt

When to Activate This Skill

Activate when user says any of:

Discovery

• "What x402 services are available?"
• "Find me an API for [task] on x402"
• "Browse the x402 Bazaar"
• "What services cost less than $0.01?"
• "Find a weather API I can pay per call"
• "What MCP tools are on x402?"
• "Show me x402 services under [price]"
• "Search x402 for [keyword]"

Paying for services

• "Call this x402 endpoint: [url]"
• "Pay for and call [service name]"
• "Use x402 to get [data] — find and pay the cheapest service"
• "Make a paid x402 request to [url]"

Do NOT activate for:

• Checking agent's own wallet balance → use /agent-wallet skill
• Listing on the Bazaar as a seller → manual setup, see seller section below
• Alpaca or stock trading → use /alpaca-trading skill

Exact Commands

List all available services

cd ~/clawd/skills/x402-bazaar && python3 agent.py "list services"

Search by keyword

python3 agent.py "find weather"
python3 agent.py "search for AI inference"
python3 agent.py "find web scraping services"

Filter by max price

python3 agent.py "services under 0.01"
python3 agent.py "services under 0.001 USDC"

Filter by type

python3 agent.py "list http services"
python3 agent.py "list mcp tools"

Inspect a specific service

python3 agent.py "inspect https://api.example.com/x402/weather"

Call a discovered service (requires EVM_PRIVATE_KEY + USDC)

python3 agent.py "call https://api.example.com/x402/weather?location=NYC"
python3 agent.py "pay and call https://api.example.com/x402/sentiment"

Full autonomous flow: find + pay + use

python3 agent.py "find the cheapest weather API and get weather for London"
python3 agent.py "find a web scraping API and scrape https://example.com"

How x402 Payment Works

1. Agent discovers a service from the Bazaar catalog
2. Calls the endpoint — gets HTTP 402 Payment Required response
3. Reads payment requirements from the 402 response headers
4. Pays via facilitator using USDC on Base
5. Retries the exact same request with payment proof header
6. Service verifies proof and returns paid result

No accounts, no subscriptions, no API keys — just USDC per request.

MCP Integration

This skill can be integrated with Model Context Protocol (MCP) servers to enable Claude Desktop and other MCP clients to autonomously pay for and use x402 APIs.

See the full MCP integration guide: x402-MCP.md

Key capabilities:

• Expose x402 services as MCP tools in Claude Desktop
• Automatic payment handling when Claude calls an API
• Support for both EVM (Base) and Solana networks
• No manual payment steps — fully autonomous

Example: Claude can discover weather APIs via this skill, then call them via MCP with automatic USDC micropayments on Base.

Facilitators Queried

Both are queried and merged when you run "list services".

Output Format

Service list:

🛒 x402 Bazaar — 42 services found

 1. 🌐 Weather API
    URL:      https://api.weather-x402.com/current
    Type:     http GET
    Price:    $0.001 USDC
    Network:  Base (eip155:8453)
    Updated:  2h ago

 2. 🤖 Llama 3.3 70B Inference
    URL:      https://api.x402network.com/llm/llama
    Type:     http POST
    Price:    $0.005 USDC
    Network:  Base (eip155:8453)
    Updated:  4h ago

Paid call result:

💸 x402 Payment Executed
   Endpoint:  https://api.weather-x402.com/current
   Paid:      $0.001 USDC
   Network:   Base (eip155:8453)
   TxHash:    0xabc123...
   Status:    200 OK

📦 Response:
   {"temperature": 72, "conditions": "sunny", "humidity": 45}

Spending Limits

Default max spend per call is $0.10 USDC. Set in .env:

MAX_SPEND_PER_CALL=0.10

The skill refuses any call where maxAmountRequired exceeds this limit and asks the user to confirm before proceeding.

Error Handling

Supported Networks (v1.0)

• Base mainnet: eip155:8453 (real USDC)
• Base Sepolia: eip155:84532 (test USDC — use for testing)

Solana support planned for v1.1.

Listing Your Own API (Sellers)

To list your x402 API on the Bazaar (v2 spec-compliant):

1. Add bazaarResourceServerExtension to your x402 resource server
2. Use declareDiscoveryExtension() in your route configuration
3. Set maxAmountRequired in your accepts[] entries (replaces v1 amount field)
4. Listing is free — services set their own per-call price

The v2 discovery API returns:

{
  "x402Version": 2,
  "items": [...],
  "pagination": {...}
}

Note: This skill handles both v1 (flat list) and v2 (wrapped response) for resilience.

MCP tool uniqueness: For MCP servers, uniqueness is determined by (resource_url, tool_name), not just the URL, since one MCP server can host multiple tools.

Full seller guide: docs.cdp.coinbase.com/x402/bazaar