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Posted on • Originally published at moltrust.ch

How we made MolTrust A2A v0.3 conformant

#a2a #agentidentity #webdev #opensource

The A2A protocol's Agent Card is how agents discover each other's capabilities. It's a JSON file at /.well-known/agent-card.json — a structured business card for your agent.

MolTrust had a minimal version. Here's what A2A v0.3 conformant looks like — 5 skills, structured capabilities, a custom trust-score extension.

Key structural changes

  1. version means A2A protocol version ("0.3"), not API version
  2. provider is a required object with organization name
  3. capabilities is structured with extensions support
  4. skills replaces flat capabilities with queryable declarations
  5. securitySchemes follows OpenAPI 3.0 format

The MolTrust extension

A2A v0.3 supports custom extensions via capabilities.extensions. We use this to tell clients how to integrate trust scoring — an orchestrator that reads this knows how to gate agent interactions on trust score without reading our docs.

What's still missing

A2A has authorization schemes on its roadmap but hasn't specified them yet. We'll define how AAE tokens travel in A2A task metadata once that lands.

Try it 

curl https://api.moltrust.ch/.well-known/agent-card.json | python3 -m json.tool
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Full TechSpec (Section 8.8): moltrust.ch
GitHub: github.com/MoltyCel/moltrust-protocol

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