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

A2A / Agent2Agent Protocol vs Pi MCP Adapter

A2A / Agent2Agent Protocol leads on trust: 89.1/100 (Grade A) against 76.0/100 (Grade B), a 13.1-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 89.1

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

a2aproject/A2A · #30 overall · #3 Protocols & Tool Integration · coverage A (4/5)

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

+10.1Safety / Integrity: 100% of recent commits signed, against 93%
+7.2Identity / Provenance: package provenance attested, against none
+4.3Adoption: 2.9M weekly downloads against 278.1k
+1.5Transparency: OSSF Scorecard 7.1 against 5.3

B Pi MCP Adapter 76.0

Token-efficient MCP adapter for Pi coding agent

nicobailon/pi-mcp-adapter · #211 overall · #8 Protocols & Tool Integration · coverage B (3/5)

Choose Pi MCP Adapter if maintenance matters most.

+3.4Maintenance: last push today, against 1d ago

Where they differ

21.4

Safety / IntegrityA2A / Agent2Agent Protocol +10.1

11.3

18.0

Identity / ProvenanceA2A / Agent2Agent Protocol +7.2

10.8

14.5

TransparencyA2A / Agent2Agent Protocol +1.5

13.0

16.6

MaintenancePi MCP Adapter +3.4

20.0

19.2

AdoptionA2A / Agent2Agent Protocol +4.3

14.9

-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	89.1	76.0
Evidence grade	A	B
Coverage grade	A	B
Overall rank	#30	#211
Rank in Protocols & Tool Integration	#3	#8
GitHub stars	26.0k	1.6k
Last updated	1d ago	today
Build provenance	Yes	No
OSSF Scorecard	7.1 / 10	5.3 / 10
License	Apache-2.0	MIT
Downloads	2.9M/wk	278k/wk
Trust dimensions (points earned)
Safety / integrity / 25	21.4	11.3
Identity & provenance / 18	18.0	10.8
Transparency / 17	14.5	13.0
Maintenance / 20	16.6	20.0
Adoption / 20	19.2	14.9
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 →