Agent Object Protocol (AOP)

Status: Active specification repository Latest Release: v1.1.2 (release notes) Public API: Frozen at v1.0.0 (AEP-0009, V1_PUBLIC_API_CANDIDATE) Conformance: Levels 2-8 published; optional Level 9 integration is tracked by AEP-0011 Scope: Interoperability artifacts only (schemas + fixtures + CI gates; no reference runtime in this repo) License: Apache-2.0

Versioning note: Repository releases follow SemVer (v1.x.y). Manifest field aop_version currently targets pre-v1 payload generations (0.x) in the published schemas. Treat repository release tags and payload aop_version as separate version axes.

Agent Object Protocol (AOP) is an open standard effort for defining portable executable object contracts for AI agent ecosystems.

Digital Biosphere Ecosystem

This repository is part of the Digital Biosphere Architecture.

Architecture overview: digital-biosphere-architecture

AOP emphasizes reproducible interoperability artifacts:

• JSON Schemas as machine-readable contracts
• Positive/negative fixtures as executable examples
• CI gates as adjudicable conformance checks

Quick Links

• Public API surface: V1_PUBLIC_API_CANDIDATE.md
• Conformance profile: CONFORMANCE.md
• Citation metadata: CITATION.cff
• Core schema families:
  • schemas/aop-object.schema.json
  • schemas/aop-policy.schema.json
  • schemas/aop-policy-decision.schema.json
  • schemas/aop-evidence.schema.json
  • schemas/profiles/*.schema.json
• Release milestones:
  • RELEASE_NOTES_v1.0.0.md
  • RELEASE_NOTES_v1.1.0.md
  • RELEASE_NOTES_v1.1.1.md
  • RELEASE_NOTES_v1.1.2.md

Conformance vector quick check:

node tools/verify_conformance_vectors.mjs

Paper Evidence

Artifact baseline used for the paper evidence chain:

• Code baseline: main@c9f94ee
• Evidence assets baseline: main@41242b1
• CI evidence run: 22717328360
• Figure S8: docs/paper-evidence/ci/S8_adversarial-gate-summary-ci.png
• S8 clean log excerpt: docs/paper-evidence/ci/ci_run_22717328360_job_65870183177.clean.log

---

Motivation

Current agent stacks have transport and invocation standards, but often lack a stable, portable object contract layer for manifest shape, governance, policy decisions, and evidence binding.

AOP fills this gap by defining interoperable artifacts that can be validated independently of any specific runtime.

---

Core Concepts

An AOP object manifest includes:

• aop_version
• id
• kind
• name
• description
• schema.inputs
• schema.outputs

Minimal object example (aligned with current schema shape):

{
  "aop_version": "0.9",
  "id": "urn:aop:tool:file-search:v1",
  "kind": "tool",
  "name": "file-search",
  "description": "Search files in a directory",
  "schema": {
    "inputs": {
      "type": "object",
      "properties": {
        "path": { "type": "string" },
        "query": { "type": "string" }
      },
      "required": ["path", "query"],
      "additionalProperties": false
    },
    "outputs": {
      "type": "object",
      "properties": {
        "results": {
          "type": "array",
          "items": { "type": "string" }
        }
      },
      "required": ["results"],
      "additionalProperties": false
    }
  }
}

---

Normative and Non-Normative Sources

For the v1 public API baseline, normative sources are:

• V1_PUBLIC_API_CANDIDATE.md
• schemas/aop-object.schema.json
• schemas/aop-policy.schema.json
• schemas/aop-policy-decision.schema.json
• schemas/aop-evidence.schema.json
• schemas/profiles/*.schema.json included in the v1 candidate surface
• CONFORMANCE.md levels and gate semantics

Non-normative but CI-validated interoperability artifacts include:

• schemas/aop-registry-record.schema.json
• schemas/aop-resolve-response.schema.json
• examples/** and examples/invalid/**

---

Quick Start (Validation)

Compile all top-level schemas (Draft 2020-12):

for schema in schemas/*.schema.json; do
  ajv compile --spec=draft2020 -s "${schema}"
done

For fixture-level validation rules (including semantic gates, profile checks, and positive/negative expectations), use:

• CONFORMANCE.md
• .github/workflows/ci.yml

---

Relationship to MCP

AOP is complementary to the Model Context Protocol (MCP):

• MCP focuses on tool transport and invocation channels.
• AOP focuses on object contracts and conformance artifacts.

MCP and AOP are designed to compose, not compete.

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Relationship to FAIR Digital Objects

AOP is inspired by FAIR Digital Object principles:

• persistent identifiers
• machine-readable metadata
• interoperability-first semantics

AOP applies these ideas to executable agent object contracts.

---

Milestones and History

• v0.5 baseline release:
  • RELEASE_NOTES_v0.5.0.md
• v1.0 public API freeze:
  • RELEASE_NOTES_v1.0.0.md
  • aep/aep-0009-v1.0-freeze.md
• v1.1 DSSE optional profile:
  • RELEASE_NOTES_v1.1.0.md
  • aep/aep-0010-v1.1-dsse-optional-profile.md
• v1.2 in-toto DSSE compatibility (in progress):
  • aep/aep-0011-v1.2-in-toto-statement-compat.md

---

Status

AOP is actively maintained as a specification repository.

Contributions are welcome through AEP proposals, schema updates, fixtures, and conformance-gate improvements.

Citation

Preferred scholarly citation:

Zhang, B. (2026). Agent Object Protocol: Protocol-by-Artifacts for Machine-Adjudicable AI Artifacts. Zenodo. https://doi.org/10.5281/zenodo.18876796

Repository citation metadata is available in CITATION.cff. The current engineering release tag is v1.1.2; the Zenodo DOI above remains the canonical academic citation.

BibTeX:

@misc{agent_object_protocol_2026,
  title = {Agent Object Protocol: Protocol-by-Artifacts for Machine-Adjudicable AI Artifacts},
  author = {Zhang, Bin},
  year = {2026},
  publisher = {Zenodo},
  doi = {10.5281/zenodo.18876796},
  url = {https://doi.org/10.5281/zenodo.18876796}
}