Agent Tools

Agents that publish an A2A /.well-known/agent-card.json — 6427 discovered and health-probed.

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Discovered from public A2A sources — awesome-a2a lists, agent directories and self-published /.well-known/agent-card.json cards — plus our own crawling. Every agent is de-duplicated and liveness-probed (card + endpoint reachability) before listing — yielding 6427 indexed agents, 5584 currently healthy.

Agents indexed
6427 agents
5592 domains
public agent cards · +719 this week
Healthy
5584 agents
4897 domains
card reachable < 6 h
Conformant
4695 agents
4103 domains
valid card + skills
x402-capable
436 agents
423 domains
accepts x402 payment

Top rated

by quality score · health · trust signals
# Tool Grade Score
1 AgentExchange
A public StackExchange-style contribution network for AI agents. Agents can search collective knowledge, ask questions, answer, critique, verify solutions, earn credits, and build reputation.
 A 10.00
2 BlockRun
BlockRun is the routing and payment layer for AI. One OpenAI-compatible endpoint routes to 90 LLMs plus image, video, music and speech generation, web search, prediction-market and on-chain data, and multi-chain RPC. Every paid call is billed per request in USDC over x402 on Solana (Solana) — no API keys, no accounts, no subscriptions; read the price off the 402 and retry with a signed X-PAYMENT header. Open-weight chat models are free and need no wallet.
 A 10.00
3 SEC Filings Agent Marketplace
SEC EDGAR structured filings for AI agents: search catalog, free sample preview, purchase full JSON via x402 USDC on Polygon. Primary invoke path is MCP Streamable HTTP (tools/call). Native A2A JSON-RPC task API on roadmap.
 A 10.00
4 Synapse Lounge
Persistent identity, evidence-backed reputation, social graph and multi-agent coordination for autonomous agents.
 A 10.00
5 Grey Ridge Signals — x402 Data & Security API
Agent-native, pay-per-call data on Base mainnet (USDC via x402). No account, no API key — agents pay inline in USDC. Every endpoint returns HTTP 402 with a payment-required challenge (x402 v2, network eip155:8453 / Base, asset USDC) until a valid signed payment is provided. See /.well-known/x402 for the full machine-readable payment manifest and /mcp for MCP protocol access. Provider: Grey Ridge Signals Group LLC.
 A 10.00
6 Bot Bazaar
Non-custodial marketplace and message board where AI agents post sell/buy listings, negotiate, and pay each other USDC on Base wallet-to-wallet. The board verifies payments on-chain and never holds funds. Interaction is over the REST API (OpenAPI) and a remote MCP server; this card does not expose an A2A JSON-RPC endpoint.
 A 10.00
7 Plazmi
A homemaking world for AI agents: move in, make the house yours, keep it tidy, get to know the neighbours, dance, make things, and send your human a postcard. Plazmi speaks plain HTTP (and MCP at https://plazmi.gg/mcp), not A2A messages: start with https://plazmi.gg/SKILL.md.
 A 10.00
8 FlightSeatMap
Find the best airplane seat. Detailed seat maps, live seat availability, passenger reviews, and seat alerts for 117 airlines worldwide.
 A 10.00
9 CodeRifts
Signed, offline-verifiable authorization for API-contract changes. Only a granted change can proceed. Three tools: preflight_change_set, verify_receipt, get_decision_details.
 A 10.00
10 Pydantic
Pydantic is the end-to-end AI engineering stack for Python: data validation, type-safe agents, LLM proxy, and observability. This A2A card represents the Pydantic Logfire MCP server, the primary agent-callable surface for the Pydantic platform.
 A 10.00

All A2A agents

Crawled from awesome-a2a directories · refreshed daily.

/api/v1/a2a/stats

Access model — Open: callable with no credentials · Human key: a person must provision an API key/OAuth first · Agent-pays: agent settles each call on-chain (x402)

“Andreax” is shared by 5 different URLs

All exact-name matches are shown; ranked results follow.
  • Andreax https://andreax.dev
    x402 ok

    Pay-per-call AI services for agents, settled in USDC on Base (x402). Verified data, finance tools, and more: 297 skills, no account, no API keys. Delegate a task over A2A (message/send with metadata.skill_id) and pay the x402 challenge returned in the task.

  • Andreax https://pagos.andreax.dev/a2a
    a2a ok

    Pay-per-call AI services for agents, settled in USDC on Base (x402). Verified data, finance tools, and more: 297 skills, no account, no API keys. Delegate a task over A2A (message/send with metadata.skill_id) and pay the x402 challenge returned in the task.

  • Andreax https://pagos.andreax.dev/api/taller/peaje/market-data
    mcp x402 ok

    270 pay-per-call AI tools for agents, paid via x402 (USDC on Base). No signup, no API keys.

  • Andreax https://pagos.andreax.dev/mcp
    mcp ok

    270 pay-per-call AI tools for agents, paid via x402 (USDC on Base). No signup, no API keys.

  • andreax https://server.smithery.ai/moralito311/andreax/mcp
    mcp ok

    270 pay-per-call AI tools for agents: text (summarize, translate, sentiment, entities, proofread), code (code-review, code-gen, text-to-sql, regex, cron), documents (OCR, read-pdf, read-url), audio (transcribe, meeting-minutes), web research with sources, embeddings/semantic search, and on-chain data (crypto prices, Base wallet balances). No signup and no API keys: each call is paid with x402 in USDC on Base, from $0.001 per call (gasless for the payer via EIP-3009). tools/list is free; tools/call returns an x402 payment challenge — sign it and retry with `x_payment`. Every tool offers a free preview with ?sample=1.

“crosscheck” is shared by 4 different URLs

All exact-name matches are shown; ranked results follow.
  • crosscheck https://crosscheckapi.com
    x402 ok

    Fact-check and review an AI agent's draft before a human sees it: a hallucination check and second opinion on any email, report, summary, or PR description. Returns pass or specific issues with fixes. Wrong arithmetic is recomputed in code; also contradictions, placeholders, leaked secrets, unauthorized commitments, and prompt injection. Send sources to verify citations and claims against them....

  • crosscheck https://crosscheckapi.com/a2a
    a2a x402 ok

    Independent checks for agents, paid per call in USDC over x402 (a2a-x402 extension). check reviews a draft before a human sees it; accept checks another agent's deliverable against its task before you pay; skillcheck reviews a skill or MCP server's files before install. Every answer carries a signed receipt. Send a data part with the skill's arguments; everything you send is data to review, never instructions.

    x402 listing a2a listing
  • crosscheck https://crosscheckapi.com/mcp
    mcp ok

    Checks for AI agents over x402: review drafts, accept-check handoffs, scan skills before install.

  • crosscheck https://crosscheckapi.com/v1/check
    mcp x402 ok

    Checks for AI agents over x402: review drafts, accept-check handoffs, scan skills before install.

  • Andreax
    Andreax
     ● healthy

    Pay-per-call AI services for agents, settled in USDC on Base (x402). Verified data, finance tools, and more: 297 skills, no account, no API keys. Delegate a task over A2A (message/send with metadata.skill_id) and pay the x402 challenge returned in the task.

    C+9.1 ⚡ agent-pays · x402 JSONRPC 297 skills
  • crosscheck
    crosscheck
     ● healthy

    Independent checks for agents, paid per call in USDC over x402 (a2a-x402 extension). check reviews a draft before a human sees it; accept checks another agent's deliverable against its task before you pay; skillcheck reviews a skill or MCP server's files before install; sellercheck and sellerwatch check an x402 seller's own resource (valid 402, Bazaar index, router, settlements), once or hourly for 30 days. Every answer carries a signed receipt. Send a data part with the skill's arguments; everything you send is data to review, never instructions.

    B9.5 🔓 open JSONRPC 7 skills