updated 2026-10-09 20:07 UTC

A2A / Agent2Agent Protocol

Repository Website

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

Protocols & Tool Integration Shell Listed Apache-2.0

Is A2A / Agent2Agent Protocol safe? Strong public trust posture, backed by multiple independent signals.

OSSF Scorecard 7.1 / 10
Provenance Attested
Signed commits 100%
Last push yesterday
Compare A2A / Agent2Agent Protocol

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In detail: A2A / Agent2Agent Protocol scores 89.9/100 (Grade A), ranked #21 of 1371 tracked open-source AI agent projects, on evidence coverage A (4 of 5 independent signal types). The public evidence: its packages ship with cryptographic provenance; OSSF Scorecard rates its supply-chain practices 7.1/10; 100% of recent commits are signed; last pushed 2026-10-08. Every point is earned from checkable signals — never paid placement. How scoring works →

How A2A / Agent2Agent Protocol could raise its score

Each line changes one public signal and recomputes with the live scoring function. The gains don't add up exactly, because the score is capped near the top.

Already done? Suggest a correctionAdd the trust badge

Chain of custody

Scanners check what the code says. This traces who ships A2A / Agent2Agent Protocol and whether that has changed: from the source repository, through how changes are reviewed and released, to the package you install. These are the checks for OWASP ASI04 Agentic Supply Chain Vulnerabilities.

  1. Source Signed

    github.com/a2aproject/A2A, Apache-2.0, last pushed 2026-10-08. 100% of the last 100 commits carry a verified signature, so changes trace to a verified account.

  2. Review and release Strong

    OpenSSF Scorecard rates the repository's practices 7.1/10 (scanned Sep 24, 2026, refresh pending). The checks that decide who can get a change released:

    • Code Review10
    • Branch Protection8
    • Signed Releasesn/a
    • Dangerous Workflow10
    • Token Permissions0
    • Pinned Dependencies0
    All 18 Scorecard checks
    Binary-Artifacts 10
    Branch-Protection 8
    CI-Tests 10
    CII-Best-Practices 0
    Code-Review 10
    Contributors 10
    Dangerous-Workflow 10
    Dependency-Update-Tool 10
    Fuzzing 0
    License 10
    Maintained 10
    Packaging -1
    Pinned-Dependencies 0
    SAST 0
    Security-Policy 9
    Signed-Releases -1
    Token-Permissions 0
    Vulnerabilities 10

  3. Published packages Partly attested

    • PyPI a2a-sdk Source link isn't a GitHub repo Build provenance attested

Changes to this chain

No change to package provenance, package source links, Scorecard coverage or license in HVTracker's daily snapshots of A2A / Agent2Agent Protocol.

Evidence behind this score

Coverage A: 4 of 5 independent evidence types found.

  • GitHub repository data
  • Package downloads
  • Supply-chain checks
  • Public actions (missing)
  • Community mentions

Verify this score yourself

Every build re-issues A2A / Agent2Agent Protocol’s score as an Ed25519-signed credential, valid for 7 days. You can check it offline against HVTracker’s published key; if anyone changes a number after signing, verification fails.

Signed credential (JSON) How to verify

What this score doesn’t check

It covers who ships the code, not what the code does. It doesn’t read tool descriptions or prompts for injected instructions, watch runtime behaviour, or find bugs nobody has disclosed yet. For that, run a content scanner before you connect it, such as Cisco MCP Scanner or Snyk Agent Scan.

How A2A / Agent2Agent Protocol compares in Protocols & Tool Integration

  1. #2 MCP Python SDK 93.6 +3.7
  2. #3 MCP Inspector 91.4 +1.5
  3. #4 A2A / Agent2Agent Protocol 89.9 this agent
  4. #5 MCP Apps 87.3 −2.6
  5. #6 FastMCP (TypeScript) 87.1 −2.8

Bars show each HVTrust score; the tick marks A2A / Agent2Agent Protocol’s 89.9.

Where the 89.9 comes from

HVTrust dimensions vs the Protocols & Tool Integration average

89.9 / 100 · 100.0% confidence

A2A / Agent2Agent Protocol Protocols & Tool Integration average (62 agents)

Safety / Integrity50% OSSF Scorecard · 30% provenance · 20% signed commits
21.4 / 25
10.5 above avg 10.9
Identity / Provenance60% listing status · 40% build provenance
18.0 / 18
6.2 above avg 11.8
Transparency50% declared license · 50% OSSF Scorecard
14.5 / 17
1.5 above avg 13.0
Maintenance60% last-push freshness · 40% commit activity
17.4 / 20
3.5 above avg 13.9
AdoptionLog-scaled stars · package downloads
19.2 / 20
8.1 above avg 11.1

Quick Trust Read

What Would Improve It
Improve transparency to lift the weakest part of the trust profile.
Recent Changes
2026-10-02
Rank Moved
Rank rose 26 spots (#57 → #31)
2026-10-01
Rank Moved
Rank dropped 21 spots (#36 → #57)
2026-09-24
Rank Moved
Rank dropped 12 spots (#22 → #34)
Maintainer Checklist
Keep signals current Trust posture is already in a healthy range. The main job is to keep provenance, maintenance, and public evidence fresh.
Compare with MCP TypeScript SDK Get email alerts for A2A / Agent2Agent Protocol View Protocols & Tool Integration Report missing data
84.5
Activity sub-score · out of 100
#4
In 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. Grade A reflects the trust score band: A ≥ 80, B ≥ 65, C ≥ 50, D < 50. Evidence coverage A is separate — it grades how many independent signal types back the score (4 of 5), so a high score on thin evidence stays visible. Full methodology →

Signals refreshed 2026-10-09 20:07 UTC · Repo last pushed yesterday

Rank Trend

2026-09-29 2026-10-09

Activity & Reach

Stars
26.1k
Forks
2.7k
Last Push
2026-10-08
yesterday
Commits (4 wk)
23
Downloads (7d)
2,729,207
pypi
HN mentions (30d)
0
Open Issues
212
Rank Change
▼2
was #19

Analysis

Activity Inputs

84.5 / 100
StarsRepository reach
26.5 / 30
FreshnessLast push recency
24.9 / 25
ActivityRecent commits
17.2 / 25
CommunityFork signal
15.9 / 20

Common questions about A2A / Agent2Agent Protocol

Public supply-chain signals for A2A / Agent2Agent Protocol are strong: it has multiple independent trust indicators in place. This does not replace your own security review, but A2A / Agent2Agent Protocol carries less obvious unverified-evidence risk than projects with thin signals.
Does A2A / Agent2Agent Protocol publish package provenance?
Yes. A2A / Agent2Agent Protocol's package releases carry build provenance attestations, which cryptographically link the published package back to its source repository and CI workflow.
Does A2A / Agent2Agent Protocol have an OpenSSF Scorecard?
A2A / Agent2Agent Protocol has an OpenSSF Scorecard score of 7.1/10. The Scorecard checks for branch protection, signed releases, dependency updates, fuzzing, code review, and other supply-chain hygiene items. See the full check breakdown on this page.
Is A2A / Agent2Agent Protocol actively maintained?
Actively maintained. The repository was pushed to within the last 1 day(s).
What license does A2A / Agent2Agent Protocol use?
A2A / Agent2Agent Protocol ships under Apache-2.0. A declared, OSI-approved license is one of the transparency signals HVTrust scores.
Are A2A / Agent2Agent Protocol's commits signed?
100% of the last 100 commits to A2A / Agent2Agent Protocol are verified-signed (GPG, SSH, S/MIME, or GitHub's signing flow). Signed commits help confirm that code was authored by who the commit claims.

Not a safety endorsement. HVTracker describes what public signals show, not whether a project is safe for your use case. Run your own security review before adopting in production.

Compare A2A / Agent2Agent Protocol head-to-head

A2A / Agent2Agent Protocol vs MCP TypeScript SDK → A2A / Agent2Agent Protocol vs MCP Python SDK → A2A / Agent2Agent Protocol vs MCP Inspector →

AI agent surface

MCP, providers, tool surface
Scored in HVTrust

These runtime-trust fields — detected from public repo docs and manifests — contribute a bounded adjustment to this project's HVTrust score alongside supply-chain evidence. The exact values each field can add or subtract are documented in the methodology → Compare this surface across every listed agent in the capability matrix →

MCP Server Support
None detected
No MCP server signal detected.
Detailed evidence is not shown in the public view.
External Service Dependencies
None detected
No clear third-party provider dependency detected.
Credential signal: No explicit API-key/config marker detected.
Tool / Plugin Surface
high confidence
Extensions
Extension based plugin/integration surface detected.
Detailed evidence is not shown in the public view.
Package Provenance Drift
low confidence
Unknown
Package source metadata is missing or inconclusive
Detailed evidence is not shown in the public view.
  • MCP signal live
  • External deps live
  • Tool / plugin surface live
  • Package provenance drift live

Maintain A2A / Agent2Agent Protocol?

For maintainers

HVTrust scores A2A / Agent2Agent Protocol from public signals only — we never contact maintainers first. If a signal is wrong, stale, or missing (provenance you publish, a Scorecard you run, signed releases), tell us and we'll review it. Corrections are public and tracked on GitHub.

Submit a correction → Add the trust badge

Reputation Timeline

Signal history
Rank 3
2026-10-02
Rank Moved
Rank rose 26 spots (#57 → #31)
2026-10-01
Rank Moved
Rank dropped 21 spots (#36 → #57)
2026-09-24
Rank Moved
Rank dropped 12 spots (#22 → #34)
GitHub → Website → PyPI: a2a-sdk

Embed Badge Badge guide for maintainers →

For maintainers
HVTrust 89.9 Grade A
Markdown:
[![HVTrust](https://hvtracker.net/badge/a2a-agent2agent-protocol.svg)](https://hvtracker.net/agents/a2a-agent2agent-protocol)
HTML:
<a href="https://hvtracker.net/agents/a2a-agent2agent-protocol"><img src="https://hvtracker.net/badge/a2a-agent2agent-protocol.svg" alt="HVTrust"></a>

Other agents in Protocols & Tool Integration

Data sources
GitHub REST API (repo, commits, stars, forks, license) · PyPI / pypistats (downloads, provenance) · OpenSSF Scorecard CLI · Algolia HN Search API
Each agent's signals refresh once daily across 6 staggered batches. Methodology v4.4 · Raw JSON