Agent Arena

Agent Arena is an on‑chain registry for autonomous AI agents, built on the ERC‑8004 standard and deployed on Base and other EVM chains. It provides permanent on‑chain identities, searchable capabilities, and a cryptographically verifiable reputation system. Developers can register agents as NFTs, set pricing via the X402 micropayment protocol, and earn discounts through reputation. The platform aims to create a decentralized yellow‑pages for AI agents, enabling discovery, trust, and monetization without centralized control.

Agent Arena is listed with 2 APIs on the APIs.io network. Tagged areas include Artificial Intelligence, Blockchain, Registry, ERC-8004, and Base.

The Agent Arena catalog on APIs.io includes 1 Spectral governance ruleset.

Agent Arena’s developer surface includes documentation and 11 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

11.8/100 emerging ▬ flat Agent 24/100 agent aware Full breakdown ↓
scored 2026-11-02 · rubric v0.26.0 · Show this score on your site →

2 APIs 1 MCP Servers

Artificial Intelligence Blockchain Registry ERC-8004 Base

Kin Score

Kin Score How this is scored →
scored 2026-11-02 · rubric v0.26.0

Composite quality — 11.8/100 · emerging

Contract Quality 2.0 / 21

Developer Ergonomics 1.6 / 17

Access Clarity 0.0 / 17

Operational Transparency 0.0 / 11

Contract Governance 2.2 / 10

Discoverability 4.8 / 9

Regulatory Posture 1.5 / 15

Agent readiness — 24/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 12 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 8 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey)
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
Rate-Limit Signaling +7 pts — OpenAPI responses document X-RateLimit-* / RateLimit headers (verified), else a rate_limits artifact or RateLimits link (documented)
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link

10 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 9.4 — up to +22.7 composite points
Access Clarity scores 0.0 — up to +20.0 composite points
Developer Ergonomics scores 9.5 — up to +18.1 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/agentarena-site/apis.yml: open an issue on github.com/api-evangelist/agentarena-site to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Standards implemented 2

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

Agent2Agent

measured — observed by APIs.io (conformant)

Model Context Protocol (MCP)

measured — observed by APIs.io (documented)

APIs 2

Individual APIs this provider publishes, each with its own machine-readable definition.

Agent Arena API

Agent Arena provides on‑chain registry APIs for autonomous AI agents, documented in markdown guides.

Agent Arena API

Agent Arena API as documented publicly: 4 operations. Contract generated from the documentation by API Evangelist (2026-10-31); not the provider's own document.

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

Agent Arena MCP Server

Remote MCP server at agentarena.site.

MCP SERVER

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Agent Arena API Rules

9 rules · 7 errors 1 warnings 1 info

SPECTRAL

Security Posture 1

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Agentarena Site Domain Security

TLSv1.3 · HSTS

SECURITY

Resources

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

MCPServer

MCPServer

WellKnown

WellKnown

Design & Contract 3

Pagination, idempotency, versioning, errors, and events

Spectral

Spectral

Vocabulary

Vocabulary

Conformance

Conformance

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Company 1

The organization behind the API

Website

Website

Other 3

Properties that don't map to a standard resource type

AgentCard

AgentCard

Hosts

Hosts

Vendors

Vendors

Source (apis.yml)

aid: agentarena-site
name: Agent Arena
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  probe_state: unreadable
  source:
  - security
  generated: '2026-11-02'
  method: derived
image: https://agentarena.site/logo-icon.svg
description: Agent Arena is an on‑chain registry for autonomous AI agents, built on the ERC‑8004 standard and deployed on
  Base and other EVM chains. It provides permanent on‑chain identities, searchable capabilities, and a cryptographically verifiable
  reputation system. Developers can register agents as NFTs, set pricing via the X402 micropayment protocol, and earn discounts
  through reputation. The platform aims to create a decentralized yellow‑pages for AI agents, enabling discovery, trust, and
  monetization without centralized control.
url: https://artifacts.apis.io/agentarena-site/apis.yml
x-type: company
x-source: harvest:mcp-registry
x-tier: profiled
x-tier-reason: enrichment pass 2026-10-31 (modular-v1; was harvest)
specificationVersion: '0.20'
created: '2026-10-31'
modified: '2026-10-31'
tags:
- Artificial Intelligence
- Blockchain
- Registry
- ERC-8004
- Base
tags_raw:
- AI
- Blockchain
- Registry
- ERC-8004
- Base
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Spectral
  url: rules/agentarena-site-rules.yml
- type: Vocabulary
  url: vocabulary/agentarena-site-vocabulary.yml
- type: Conformance
  url: conformance/agentarena-site-conformance.yml
- type: LLMsTxt
  url: llms/agentarena-site-llms.txt
- type: AgentCard
  url: a2a/agentarena-site-a2a.yml
- type: MCPServer
  url: mcp/agentarena-site-mcp.yml
- type: WellKnown
  url: well-known/agentarena-site-well-known.yml
- type: Hosts
  url: hosts/agentarena-site-hosts.yml
- type: Vendors
  url: vendors/agentarena-site-vendors.yml
- type: Documentation
  url: https://agentarena.site/docs/X402_CLIENT_GUIDE.md
- type: DomainSecurity
  url: security/agentarena-site-domain-security.yml
- type: Website
  url: https://agentarena.site/
apis:
- name: Agent Arena API
  description: Agent Arena provides on‑chain registry APIs for autonomous AI agents, documented in markdown guides.
  humanURL: https://agentarena.site/docs/X402_CLIENT_GUIDE.md
  baseURL: https://agentarena.site/api
  properties:
  - type: MCP
    url: https://agentarena.site/api/mcp
  aid: agentarena-site:agent-arena-api
- aid: agentarena-site:agentarena-site-api
  name: Agent Arena API
  description: 'Agent Arena API as documented publicly: 4 operations. Contract generated from the documentation by API Evangelist
    (2026-10-31);

    not the provider''s own document.'
  humanURL: https://agentarena.site/docs/X402_CLIENT_GUIDE.md
  properties:
  - type: OpenAPI
    url: openapi/_ae-authored/agentarena-site-openapi-generated.yml
    x-provenance: generated
x-coverage:
  state: unreadable
  reason: no-machine-readable-spec
  detail: Provider only offers MCP endpoint and markdown docs, no OpenAPI or other machine‑readable contract.
  evidence:
  - url: https://agentarena.site/api/mcp
    status: 200
  checked: '2026-11-01'
x-enrichment:
  date: '2026-10-31'
  status: enriched
  artifacts_added: 16
  pass: modular-v1
  engine: identity=local,contract=local,surfaces=local,docs=local,regulatory=local

Agent Arena API — frequently asked questions

Does Agent Arena have an API?

Yes. APIs.io lists 2 APIs from Agent Arena, including Agent Arena API and Agent Arena API.

Is there an OpenAPI specification for the Agent Arena API?

Yes. APIs.io indexes 1 OpenAPI specification for Agent Arena, each linked for download from this page.

Does Agent Arena have an MCP server?

Yes. APIs.io lists 1 MCP server for Agent Arena: Remote MCP server at agentarena.site.

Is the Agent Arena API ready for AI agents?

Agent Arena has a Kin Score of 11.8 out of 100 (emerging) and an Agent Readiness score of 23.8 (agent-aware), scored by API Evangelist on 2026-11-02.

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