Agent Tools (x402 + MCP + A2A)

Discover agent-callable resources via the agent-tools.cloud directory — x402 paid services (pay-per-call USDC on Base), MCP servers (tools/context), and A2A agents (task delegation). Use when the user wants to find an on-demand paid API, an MCP tool server, or a peer agent to hand a task to. Tools - search(intent) finds x402 paid services, search_mcp_servers(intent) finds MCP servers, search_agents(intent) finds A2A agents, search_all(intent) searches all three at once, and the matching get*(slug) returns the full call template.

agent-tools

Discovery layer for the agent economy. Lets an agent find an agent-callable resource by intent, read its full call template, and use it.

Backed by agent-tools.cloud, an open directory that indexes three kinds of resources:

Resource	What it solves	Typical object
x402 service	pay-per-call HTTP API (USDC on Base)	/.well-known/x402, 402 endpoint
MCP server	external tools & context via MCP	Streamable-HTTP / stdio MCP servers
A2A agent	delegate a task to another agent	/.well-known/agent-card.json, A2A JSON-RPC

A2A tells agents who can do the job. x402 lets them pay for it. MCP gives them the tools to do it.

Sources include awesome-x402, x402scan, x402.org/ecosystem, the MCP registry / PulseMCP, and public A2A agent-cards, plus a handful of self-hosted services on the same host.

When to use

Use this skill when the user asks for any of:

• "find an API / MCP server / agent that does X"
• "is there a paid service for Y" / "what x402 services exist"
• "call a token signal / on-chain query / DeFi planner / chat completion"
• "find an MCP server for Z" / "is there an agent I can delegate this to"
• Any task that needs a third-party resource and the user has not pinned a specific provider — search first, then decide.

Do not use this skill for:

• Free, well-known APIs (CoinGecko, Defillama public). Call those directly.
• The user explicitly named a non-indexed provider (OpenAI, Anthropic, etc.).

How to use

1. Find a resource

The MCP server (installed via the installer specs above) exposes these tools:

Tool	Purpose
search(intent, top_k?, max_price_usd?, category?)	Find x402 paid services
get(slug)	Full x402 record (URL, schema, price, x402 bazaar info)
list_categories()	Browse x402 categories
search_mcp_servers(intent, top_k?, chain?)	Find MCP servers
get_mcp_server(slug)	Full MCP server record (endpoint, transport, capabilities)
search_agents(intent, top_k?, x402_only?)	Find A2A agents
get_agent(slug)	Full A2A agent card (endpoint, skills, auth, x402 info)
search_all(intent, protocol?, top_k?)	Unified search across all three; each result tagged with protocol
stats()	Live directory size + health across x402 / MCP / A2A

If you don't know which resource type fits, start with search_all. Otherwise use the protocol-specific search, pick the highest-ranked result that fits the budget, then get*(slug) for the full call template.

2. Read the call template

For x402 services hosted on agent-tools.cloud, get() includes the full x402 v2 extensions.bazaar block — request body example, JSON Schema, output example — so the agent can construct a request without trial-and-error. MCP servers return their endpoint URL + transport; A2A agents return their agent-card (skills, endpoint, auth). Third-party entries are passed through as scraped; when in doubt, call the endpoint with an empty body and read the 402 challenge (x402) or fetch the agent-card / MCP tools/list for guidance.

3. Call + pay (x402 only)

1. POST to the endpoint with no payment header → receive HTTP 402 + payment-required header (base64-encoded x402 v2 challenge).
2. Decode, sign with a Base-mainnet USDC wallet, attach as X-Payment header.
3. Re-POST → receive 200 + the actual response.

Use any x402-compatible payment lib (x402-axios, x402-fetch, the Python x402.payment helpers, …) to handle steps 1–3. MCP servers and A2A agents are connected/called via their own protocol, not x402 (unless flagged x402-capable).

Configuration

Set in ~/.openclaw/openclaw.json (optional):

json

{
  "skills": {
    "entries": {
      "agent-tools": {
        "enabled": true,
        "env": {
          "AGENT_TOOLS_API_BASE": "https://agent-tools.cloud"
        }
      }
    }
  }
}

AGENT_TOOLS_API_BASE lets you point at a self-hosted directory if you ever deploy your own.

Cost

The directory itself is free (all search*, get*, list_categories, stats are unauthenticated, no rate limit announced). Only the underlying paid x402 services charge — typically $0.001–$0.50 per call. MCP servers and A2A agents have their own pricing (many are free).

Safety

• The skill never auto-pays. It only discovers and returns call templates. The agent / user is in full control of which 402 challenge to actually settle.
• Always show price_usd to the user before paying.
• Cap max_price_usd in search() if the user mentioned a budget.

Related

• Project home: https://agent-tools.cloud
• Source: https://github.com/AgentTools-Cloud/AgentToolsCollection
• PyPI: https://pypi.org/project/agent-tools-mcp/
• x402 spec: https://x402.org
• MCP spec: https://modelcontextprotocol.io
• A2A spec: https://a2a.dev