Claynsn/agent-discovery-mcp

> An MCP server that lets your AI coding agent (Claude Code, OpenClaw, Codex, Cursor, etc.) **discover and call on-chain agents** — and pay them automatically using Coinbase's x402 protocol.
Agents register themselves on ERC-8004, Ethereum's agent identity standard. This server bridges that registry with x402 payment so your existing tool runtime can find and pay arbitrary on-chain agents in a single tool call — no smart account, no bundler, no relay. Just your EOA, an HTTPS request, and an automatic 402 → sign → retry flow.
**Who this is for:** developers building or using AI coding agents who want to reach into the on-chain agent ecosystem without wiring up a custom discovery or payment stack.
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What it does
Three tools, exposed via Model Context Protocol:
| Tool | What it does | Source of truth |
|---|---|---|
| find_agents_by_skill | Search the ERC-8004 registry for agents matching a skill keyword. Returns id, chain, name, description, endpoint, and x402-support flag. | 8004scan.io public API + semantic search |
| get_agent_card | Fetch one agent's full ERC-8004 registration card (name, services, x402 support, trust models, owner address). | 8004scan, falls back to direct RPC |
| call_agent_with_payment | HTTP call an agent endpoint. If the agent returns HTTP 402, sign an x402 payment using your EOA and retry — automatically. | x402-fetch (Coinbase official) |
The whole server is ~250 lines of TypeScript. No smart contract account, no bundler, no third-party relay — payment is direct EOA signing per the x402 spec.
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Why this exists
The pieces of an agent-to-agent economy are now real:
- **x402** (Coinbase's HTTP 402-based payment protocol) processes 165M+ transactions and ~$50M in volume as of April 2026.
- **ERC-8004** (Ethereum's agent identity standard) was deployed to mainnet on January 29, 2026 and now has tens of thousands of registered agents.
- **MCP** (Anthropic's tool-call protocol) is the de-facto standard for connecting AI coding agents to external capability.
But there was no clean "glue" that lets a Claude Code / OpenClaw / Cursor user *just discover and pay* an arbitrary on-chain agent from inside their existing tool. Existing options like @azeth/mcp-server bundle ERC-4337 smart accounts and a custom trust layer on top — which forces a bundler/relay dependency that can fail in practice on testnets.
This server skips all of that. It uses:
1. **8004scan public API** for agent discovery (the canonical ERC-8004 indexer maintained by the ERC-8004 team)
2. **Coinbase's official x402-fetch** for payment — wraps native fetch to handle 402s automatically
3. **viem** for EOA signing — no contract account deployment, no bundler
The result: install, set one env var, and your agent runtime can call any x402 agent in the ERC-8004 registry.
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Current status
This is a working v0.1.0 with real infrastructure underneath it, but the ecosystem is still early.
- **Discovery works.** The 8004scan API returns real agents from the ERC-8004 registry (~70k+ registered across chains as of mid-2026).
- **Payment works.** The x402 payment flow is end-to-end using Coinbase's official x402-fetch library and EOA signing.