Agent Capability Contract (ACC)

Agent Capability Contract (ACC) is an open declaration contract for exposing business capabilities to agents.

ACC defines how a business system describes which operations an agent may see, when those operations should be considered risky, when a human approval intent is required, how an acting subject is required, and what metadata a runtime should preserve for audit and traceability.

ACC is not a runtime, a chatbot framework, or a workflow engine. It is a portable contract that can be implemented by different control planes, gateways, SDKs, developer tools, and agent runtimes.

ACC is maintained as an independent, implementation-neutral standard. No product implementation defines ACC semantics or receives privileged compatibility status.

ACC is the capability contract for A2B (Agent-to-Business): agents safely doing business work through existing systems.

ACC deliberately keeps a small normative core. See Design Rationale And Boundaries for the concerns ACC knows about but intentionally leaves to business authorization, runtime policy, approval systems, compliance policy, or other contracts.

Why ACC Exists

Existing business systems were not designed for A2B. Once an agent can call business APIs, teams need a standard way to answer:

• Which operations may be exposed to an agent?
• Which route, product surface, or scenario may use a capability?
• Does the operation require a real business subject?
• Is the operation readonly, low risk, medium risk, or high risk?
• Should specific arguments trigger a human approval intent?
• Which fields are sensitive and should be redacted from audit logs?
• How should runtime gateways preserve extension metadata without making it a security rule?

ACC puts these declarations next to the API contract, while keeping the final authorization decision inside the business system.

ACC controls reach.
The business system controls authority.

OpenAPI Binding

The first ACC binding is OpenAPI extension field:

x-agent-capability:
  version: 1
  enabled: true
  scope: order.read
  risk:
    level: low
  subject:
    required: true
  execution:
    readonly: true

See SPEC.md for the normative field model.

ACC v1 declarations use version: 1. Exact specification revisions use repository tags such as v1.0.1; product or runtime versions are separate.

Implement ACC

• Read the non-normative Implementer's Guide.
• Choose a claim from Conformance Profiles.
• Run the applicable machine-readable ACC v1 vectors.
• Publish evidence using Implementation Registration and Self-Assessment.
• Submit a pull request to the neutral implementation registry.

Repository Layout

SPEC.md                       Normative ACC v1 specification
CONCEPTS.md                   A2B and ACC terminology
bindings/openapi.md           OpenAPI extension binding
schemas/acc.v1.schema.json    Machine-readable JSON Schema
examples/                     OpenAPI examples
conformance/README.md         Implementation conformance checklist
conformance/PROFILES.md       Parser, generator, runtime, and policy profiles
conformance/SELF_ASSESSMENT.md Open registration and evidence template
conformance/v1/                Machine-readable ACC v1 conformance vectors
proposals/                     Public normative proposal process and template
IMPLEMENTER_GUIDE.md          Non-normative implementation architecture guidance
DESIGN_RATIONALE.md           Why ACC stays small and where adjacent concerns belong
DESIGN_RATIONALE.zh-CN.md     Chinese design rationale and boundaries
IMPLEMENTATIONS.md            Known implementations and claim language
RELEASE_NOTES_v1.0.1.md       Current ACC v1 patch release summary
RELEASE_NOTES_v1.0.0.md       Initial stable ACC v1 release summary
GOVERNANCE.md                 Stewardship, versioning, and extension rules
CONTRIBUTING.md               Contribution rules for contract changes
CHANGELOG.md                  Public changes
NOTICE                        Attribution notice
LICENSE                       Apache-2.0 license

Implementations

ACC is implementation-neutral. It can be implemented by control planes, API gateways, SDK generators, developer tools, agent runtimes, MCP gateways, and policy engines.

Known implementations are listed alphabetically in IMPLEMENTATIONS.md. Projects implementing ACC are welcome to publish a self-assessment and submit a pull request. Listing is not certification or endorsement.

License

ACC is licensed under the Apache License 2.0. See LICENSE.

The license allows use, modification, redistribution, and commercial implementation of ACC.