Is plain.com agent ready?
plain.com is largely agent ready: it scores 63/100 (grade B) on the w2agent rubric.
Changed since last check
+3 points since the previous check (2026-09-15)
Fixed: Response time, Reachable as Google-Agent, Reachable as ChatGPT-User
Regressed: Content negotiation (Markdown)
Category scores
Category breakdown not recorded for this audit.
Agent protocol panel
- A2A agent cardNot found
- OAuth discoveryPresent
- MCP discoveryPresent
- llms.txt validityPresent
Check results
Bot Accessibility
- ✓No error status codespass
- ✓Response timepass
- ✓XML sitemap existspass
- ✓AI agent accesspass
- ✓Edge treatment of agent user-agentstracked, not scoredpass
- ✓robots.txt existspass
- ✗Content negotiation (Markdown)fail
- —Declared AI usage preferencestracked, not scoredskip
Structured Data
- ✓OpenGraph meta tagspass
- ~Semantic HTML elementspartial
- ✗Appropriate Schema.org typefail
- ✗JSON-LD validfail
- ✗Heading hierarchyfail
- ✓Schema.org JSON-LD presentpass
- ✗Schema.org completenessfail
Content Quality
- ✓FAQ contentpass
- ✓Answer-first contentpass
- ✓Content lengthpass
- ✗Token efficiency (HTML-to-text ratio)fail
- ✗Freshness signalsfail
- ✗Author attributionfail
- ✓Citation readinesspass
- ✓Lists and tables for structured infopass
Agent Discovery
- ✓llms.txt follows specpass
- ✓llms.txt existspass
- —MCP server cardtracked, not scoredskip
- ✗Markdown alternate linksfail
- ✗/.well-known/agent-card.jsonfail
- ✓llms.txt links resolvepass
Agent Protocols
- ✓Discoverable API endpointspass
- ✓MCP endpointpass
- ✗Action schemasfail
- —/.well-known/ucpskip
- ✗Structured formsfail
- —WebMCP imperative APItracked, not scoredskip
- —WebMCP declarative APItracked, not scoredskip
- ✓Reachable as Google-Agentpass
- ✓Reachable as ChatGPT-Userpass
- ✓Reachable as Perplexity-Userpass
Agent Auth
- —MCP authorization (401 challenge → protected resource metadata)skip
- ✓PKCE S256 supportpass
- ✓Public API surfacepass
- ✓Client ID Metadata Documents (bonus)pass
- ✗OpenAPI specificationfail
- ✗Agent/bot auth documentationfail
- ✓OAuth discovery chain (RFC 9728 → RFC 8414)pass
- ✓Developer portalpass
- ✗Scoped API permissionsfail
- ✗API catalog (RFC 9727)fail
- —Agent operator signing directorytracked, not scoredskip
Technical
- ✓HTTPSpass
- ✓UTF-8 charsetpass
- ✓Canonical URLspass
- ✓Mobile viewportpass
- ✓Content accessible without JSpass
- ~Security headerspartial
Score history
- 63/100 · rubric v3.0
- 60/100 · rubric v3.0
- 60/100 · rubric v2.0
- 60/100 · rubric v2.0
- 57/100 · rubric v2.0
- 58/100 · rubric v2.0
- 51/100 · rubric v2.0
- 52/100 · rubric v2.0