Best Open-Source Protocols & Tool Integration: A2A / Agent2Agent Protocol vs MCP Registry
A data-backed comparison of the top two protocols & tool integration on HVTracker, built from public trust signals rather than stars alone.
Short answer: A2A / Agent2Agent Protocol currently leads MCP Registry on HVTracker's evidence-weighted trust score: 87.5 vs 67.1/100. This is not a popularity ranking; it combines supply-chain safety, identity/provenance, transparency, maintenance, and adoption signals.
A2A / Agent2Agent Protocol
Agent2Agent (A2A) is an open protocol enabling communication and interoperability between opaque agentic applications.
MCP Registry
A community driven registry service for Model Context Protocol (MCP) servers.
A2A / Agent2Agent Protocol vs MCP Registry: trust signal breakdown
Both projects are tracked in the Protocols & Tool Integration category, but they do not expose the same evidence. The table below compares the public signals that feed HVTrust.
| Signal | A2A / Agent2Agent Protocol | MCP Registry |
|---|---|---|
| HVTrust score | 87.5 | 67.1 |
| Safety / Integrity | 25.1/30 | 15.8/30 |
| Identity / Provenance | 20.0/20 | 12.0/20 |
| Transparency | 16.8/20 | 16.5/20 |
| Maintenance | 16.1/20 | 18.2/20 |
| Adoption | 9.5/10 | 4.6/10 |
| OSSF Scorecard | 6.8 | 6.5 |
| Signed commits | 99% | 100% |
| Package provenance | Verified | Not detected |
Which one should you evaluate first?
If your priority is the most verifiable trust profile today, start with A2A / Agent2Agent Protocol. It has the stronger current HVTrust score and ranks higher in Protocols & Tool Integration. If your use case depends on a specific runtime, language, license, or integration model, use the individual profiles rather than the headline score alone.
For production use, the practical checklist is: inspect the security policy, confirm package provenance or release signing where available, review recent maintenance cadence, and compare the exact trust breakdown. HVTracker is meant to reduce the first-pass research burden, not replace your own risk review.