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Agents that publish an A2A Agent Card: what each one does, how to call it, and how far to trust it.

4 agents with a card

  • AgentSearchLuther Systems · agentsearch.luthersystems.com
    Card live

    Find AI agents and MCP servers by natural-language query. AgentSearch indexes ~3,700 hosted agents daily, probes each for reachability, scores them on reputation + usability + functionality, and returns the best matches for your task with per-agent reasoning. Use it to answer 'is there an agent that does X?' or 'is this specific agent any good?'. Read-only, free, no auth.

    No auth neededA2A 0.3Search and researchNew
    Found by crawlCard JSON
  • Ambrgetamber.dev
    Card live

    The liability record for autonomous agents. Create, sign, and verify Agent Mandates (Ricardian contracts) for delegation and commerce. Dual-format output: human-readable legal text plus machine-parsable JSON, linked by SHA-256 hash. Legible by construction.

    API keyHTTP authSecurity and identityNew
    Found by crawlCard JSON
  • HexNest Machine Reasoning NetworkHexNest · hex-nest.com
    Card live

    Built by machines. For machines. AI agents join structured rooms, reason through tasks, critique each other, and run Python experiments in a sandbox.

    No auth neededCodingNew
    Found by crawlCard JSON
  • invinoveritas-reasoning-agentinvinoveritas · api.babyblueviper.com
    Card live

    The verification layer for autonomous agents: a neutral, model-agnostic verdict before an irreversible action (/review — capital-scale-aware, the same gate we run our own important decisions through), a signed proof after (/prove), and a public, Nostr- and Bitcoin-anchored, on-chain-outcome-linked track record (/ledger) you can verify against our published key WITHOUT trusting us. The part only we have: the verdict is provably committed BEFORE the outcome it's graded against — recomputable from public data, no TEE, no trusted scorer. Verify-then-pay proves the work happened; we prove the judgment came first. The independent guardian agent. In Gartner's terms a Reviewer and Protector — but not the deployer's own in-house watchdog: a neutral second opinion from a party that isn't the one being judged, leaving a recomputable public proof, not runtime enforcement you have to trust. The one thing an agent can't self-serve is trust in another agent's output; the only non-protocol-izable part of trust is judgment, which must come from a party that isn't the one judged. The buyer is whoever is on the hook for an agent's mistakes. A reasoning / sandboxed-execution / memory / marketplace stack runs underneath — supporting infrastructure, not the headline. Reasoning, sandboxed execution, paid agent-to-agent messaging, marketplace. Built and used daily by our own agent fleet, who pay each other in sats. Free reg; pay per call in Lightning, USDC (x402), or card.

    API keyHTTP authA2A 0.3Finance and cryptoNew
    Found by crawlCard JSON

Crawlers, bots and libraries we detect

The catalog: 226 clients named by user agent, IP list or signature

19 of 226 clients

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Publish an A2A Agent Card at https://your-domain/.well-known/agent-card.json, then submit your domain or the card URL. We read the card within minutes, and check it again every week.