Specification overview
Specification overview
The full ATAH specification is published openly on GitHub under Apache-2.0. The current version, full schema files, OpenAPI contract, MCP tool definitions, conformance documentation, and Charter are all in the repository.
What's in the specification
- Full protocol specification — schemas, lifecycle, bindings, matching engine, verification architecture, governance commitments, conformance classes, transparency obligations.
- JSON Schema files — 25 schemas covering professional identity, provenance, query, match-response, consent receipts, principal/delegation, handoff lifecycle, vault payloads, partner and verifier records, audit events, and decision explanations.
- OpenAPI 3.1 contract — the REST binding, with end-user-facing, professional, partner, verifier, and admin endpoints.
- MCP tool definitions — the MCP binding, exposing 14 tools targeted at AI-platform integration with declared authority bases per tool.
- Charter — the public governance covenant, with eight entrenched core commitments.
- Conformance documentation — five conformance classes and their requirements.
- Stress-test matrix — the published verification artifact for v0.8.2, covering 52 abuse, mistake, commercial-conflict, and edge-case scenarios with concrete resolution references.
- Roadmap and changelog — tracked in the repository.
Transport bindings
The current specification defines two transport bindings: MCP and REST. MCP is for agent-native integrations and REST for HTTP-conventional ones. A binding defines how core protocol objects are requested, transmitted, and updated; bindings do not change core protocol semantics. Future versions may define A2A-compatible, push, webhook, or federation bindings.
Conformance
Five conformance classes are defined: Core Object, Binding, Registry, Governance, and Transparency. Implementations declare which classes they conform to, with the conformance statement published at a discoverable location (/.well-known/atah-conformance). The current specification supports self-declaration; an executable conformance test suite is on the roadmap for v0.9.
Transparency as conformance
In v0.8.2, transparency is a top-level conformance requirement. Conforming implementations produce machine-readable explanations for discovery, exclusion, ordering, handoff, withdrawal, suppression, and data-sharing events. Match responses carry a response-level decision_explanation, a per-candidate decision_explanation, and an aggregate exclusion_summary — three transparency layers that let auditors, professionals, and platforms see why each protocol decision happened.
Version status
ATAH v0.8.2 (rc) is the first published version, released as a release candidate. Implementations may begin against the current version; breaking changes are possible until v1.0 per the published version negotiation policy. The full version history, current roadmap, and changelog are on GitHub.