YourAITools

Free A2A Agent Card Validator (A2A Protocol v1.0)

Find out in one command whether your agent-card.json is valid A2A v1.0, and exactly what to change if it isn't.

Free A2A Agent Card Validator (A2A Protocol v1.0) product illustration

What it does

Checks an A2A Agent Card (/.well-known/agent-card.json) against A2A Protocol v1.0, with precise messages for cards still in the v0.3 shape. Python 3.9+, standard library only.

python3 tools/a2a_validate.py agent-card.json
python3 tools/a2a_validate.py https://your-agent.example.com        # fetches the well-known card
python3 tools/a2a_validate.py agent-card.json --json --strict        # CI: exit 1 on errors or warnings

What you get

The screenshot is real output from the kit’s own commands. Tested from a fresh download of this exact zip: ./run_tests.sh ran 5 tests OK on Python 3.13 and 3.10.

Real terminal output from Free A2A Agent Card Validator (A2A Protocol v1.0): demo and passing tests

What it checks

  • Required fields: name, description, version, supportedInterfaces, capabilities, defaultInputModes, defaultOutputModes, skills.
  • Interfaces: protocolBinding (JSONRPC, GRPC, HTTP+JSON; it catches jsonrpc), Major.Minor protocolVersion (it catches 1.0.0), absolute https URLs (http is allowed only on localhost), duplicates.
  • Media types (text vs text/plain), boolean capabilities, extensions.
  • Skills: required id/name/description/tags, duplicate ids, missing examples.
  • Security: all 5 v1.0 scheme kinds, one OAuth flow per scheme, required flow URLs, deprecated implicit/password flows, PKCE, requirements that reference undefined schemes or undeclared scopes.
  • Signatures: base64url JWS header with alg (rejects none) and a key reference.
  • v0.3 leftovers (url, preferredTransport, additionalInterfaces, top-level protocolVersion, supportsAuthenticatedExtendedCard, security, OpenAPI-style type: schemes), each with the v1.0 replacement.

examples/ has a good card, a broken card (13 errors) and a v0.3 card. ./run_tests.sh runs 5 tests.

Honest limits

  • Signatures are checked for structure only: the cryptography is not verified.
  • Validation only: no automatic migration and no live JSON-RPC tests (those are in the paid kit).

Format and license

Zip, 12 KB, v1.0, 10 files. Free to use, modify and share for any purpose, including commercial work, as long as this notice stays in copies. Not affiliated with or endorsed by the A2A Project or the Linux Foundation.

FAQ

Does it fetch my live card?
Yes: pass the agent's base URL and it reads /.well-known/agent-card.json.
Can it run in CI?
Yes: --json output, exit code 1 on errors, and --strict also fails on warnings.
Does it fix the card?
No, it lists the fixes. The paid A2A Agent Card Kit migrates v0.3 cards automatically.
How do I get the files?
Click Download free. The zip downloads straight away: no checkout, no account.
Do I have to sign up for the newsletter?
No. The form is optional and the download works without it.

Get Free A2A Agent Card Validator (A2A Protocol v1.0)

Free A2A Agent Card validator: checks agent-card.json against A2A Protocol v1.0, flags v0.3 leftovers with fixes, works on files or live URLs. Python.

Free free download

Download free (zip)Or get A2A Agent Card Kit: v1.0 Validator, Migrator, Templates + Test Agent →

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