API Commons · Models · de facto
The Anthropic Messages Dialect
34 providers in the API Evangelist catalog state Anthropic compatibility. The cohort here is the 29 providers whose published OpenAPI declares at least one operation UNIQUE to the Anthropic API. That restriction matters: 29 of Anthropic's operations share a path shape with the OpenAI interface, and measuring against everyone who publishes a spec put GET /models at 86.3% — a figure that was measuring OpenAI adoption, not this one.
How it was measured
Tiers are measured against what adopters publish, not asserted. Each METHOD and path is graded by the share of the publishing cohort that declares it. Grading by path alone credits every method on a path equally, which is wrong: GET and POST on /chat/completions are not implemented at the same rate.
The core tier
What a provider has to implement before a compatibility claim means anything. Every placement is measured, and the evidence for each sits in the tier profile.
GETPOST
Adopters
| Evidence | Count | What it means |
|---|---|---|
| declared | 20 | Publishes a machine-readable spec declaring them. |
Every entry in the registry carries the URL it was read from and the date it was read. A claim is never promoted to a verdict.
Providers that reach a tier
9 of the 20 recorded adopters demonstrably reach the core tier or better.
EdgeeSail ResearchxAI0G LabsMartianosmAPIProbablRouterPlexSiliconFlow
Artifacts
Everything this standard publishes. All of it is generated from the profile, so a re-measurement moves every artifact together.
models/main/standard/anthropic-messages-v1/openapi.yml
OpenAPI Overlay
models/main/standard/anthropic-messages-v1/overlay.yml
Arazzo workflow
models/main/standard/anthropic-messages-v1/arazzo/core-conformance.yml
MCP tools
models/main/standard/anthropic-messages-v1/mcp/tools.json
Spectral ruleset
models/main/standard/anthropic-messages-v1/spectral/anthropic-profile.yaml
Adopter registry
models/main/adopters/anthropic-messages-v1.yml
Repository
models
Source
| Originator | Anthropic |
| Read from | https://github.com/anthropics/anthropic-sdk-python |
| Upstream licence | MIT |
| Pinned at | eb21a4352015686c30f5759e8c2f02d70f5371e2 |
| API Commons | https://apicommons.org/standards/models/ · https://github.com/api-commons/models |