Registry › Compare › A2A / Agent2Agent Protocol vs Pi MCP Adapter

A2A / Agent2Agent Protocol vs Pi MCP Adapter

A2A / Agent2Agent Protocol leads on trust: 89.8/100 (Grade A) against 74.7/100 (Grade B), a 15.1-point gap. A2A / Agent2Agent Protocol leads on supply-chain integrity and provenance, and rests on broader evidence; Pi MCP Adapter leads on maintenance.

A A2A / Agent2Agent Protocol 89.8

Agent2Agent (A2A) is an open protocol enabling communication and interoperability between opaque agentic applications.

a2aproject/A2A · #26 overall · #4 Protocols & Tool Integration · coverage A (4/5)

Choose A2A / Agent2Agent Protocol if supply-chain integrity and provenance matter most.

+10.8Safety / Integrity: 100% of recent commits signed, against 92%
+7.2Identity / Provenance: package provenance attested, against none
+4.1Adoption: 2.7M weekly downloads against 371.2k
+2.0Transparency: OSSF Scorecard 7.0 against 4.6

B Pi MCP Adapter 74.7

Token-efficient MCP adapter for Pi coding agent

nicobailon/pi-mcp-adapter · #261 overall · #12 Protocols & Tool Integration · coverage B (3/5)

Choose Pi MCP Adapter if maintenance matters most.

+2.4Maintenance

Where they differ

21.2

Safety / IntegrityA2A / Agent2Agent Protocol +10.8

10.4

18.0

Identity / ProvenanceA2A / Agent2Agent Protocol +7.2

10.8

14.4

TransparencyA2A / Agent2Agent Protocol +2.0

12.4

17.6

MaintenancePi MCP Adapter +2.4

20.0

19.2

AdoptionA2A / Agent2Agent Protocol +4.1

15.1

-0.6

Runtime calibrationPi MCP Adapter +6.6

+6.0

Full evidence table

An independent, evidence-based trust comparison of A2A / Agent2Agent Protocol and Pi MCP Adapter, two Protocols & Tool Integration projects in the HVTracker registry. Scores come from public, checkable signals — supply-chain provenance, OSSF Scorecard, maintenance, and adoption — not popularity.

Full evidence

Signal	A2A / Agent2Agent Protocola2aproject/A2A	Pi MCP Adapternicobailon/pi-mcp-adapter
HVTrust score	89.8	74.7
Evidence grade	A	B
Coverage grade	A	B
Overall rank	#26	#261
Rank in Protocols & Tool Integration	#4	#12
GitHub stars	26.2k	1.6k
Last updated	today	today
Build provenance	Yes	No
OSSF Scorecard	7.0 / 10	4.6 / 10
License	Apache-2.0	MIT
Downloads	2.7M/wk	371k/wk
Trust dimensions (points earned)
Safety / integrity / 25	21.2	10.4
Identity & provenance / 18	18.0	10.8
Transparency / 17	14.4	12.4
Maintenance / 20	17.6	20.0
Adoption / 20	19.2	15.1
Runtime capability surface (full matrix)
MCP server	—	Implemented
External providers	—	—
Requires API keys	No	No
Plugin surface	extensions	—
Provenance drift	Unknown	Match

Open in the live compare tool → A2A / Agent2Agent Protocol profile Pi MCP Adapter profile More Protocols & Tool Integration →

How to read this: HVTrust (0–100) weighs supply-chain signals (provenance, OSSF Scorecard, signed commits, open license) alongside real-world adoption, scaled by an evidence-confidence factor. Grade bands: A ≥ 80, B ≥ 65, C ≥ 50, D < 50. Signals refresh daily. Full methodology v4.4 →