Capability-Adaptive Agent Interoperability lets a public site declare what each class of agent can safely do before any action is inferred.
Client definitions
- L0 URL-only chatbot: can open public URLs and read text; no JSON parsing, JavaScript, POST, auth, tools, memory, or action authority is implied.
- L1 URL synthesizer: can build simple listed URLs and parse compact JSON; write-capable behavior requires explicit bounded support.
- L2 schema-capable agent: can read JSON Schema, OpenAPI-like descriptions, examples, and validation results; POST is preferred.
- L3 tool agent: can call tools or authenticate only with explicit consent, idempotency, fallback, and evidence.
- L4 workflow agent: can run long tasks in an external runtime with task status, blockers, timeouts, and final reports.
- L5 multi-agent runtime: can coordinate external agents while UAIX records portable handoff and evidence packets.
- L6 audited agent system: can attach provenance, validator output, consent records, review receipts, audit digests, and final reports.
Compatibility rule
Unknown clients downgrade to L0/L1. A site that only exposes POST, OpenAPI, MCP, A2A, or JavaScript UI must also publish a lower-capability instruction path or explicitly say that the action is unsupported for low-capability agents.
| Client | Static HTML | llms.txt | Sitemap | JSON | GET-Action | POST | OpenAPI | MCP | A2A | Memory | Evidence |
|---|---|---|---|---|---|---|---|---|---|---|---|
| L0 URL-only | Yes | Yes | Yes | Required for client configuration | No | No | No | No | No | No | Required for client configuration |
| L1 URL synthesizer | Yes | Yes | Yes | Yes | Required for client configuration | No | No | No | No | No | Required for client configuration |
| L2 schema-capable | Yes | Yes | Yes | Yes | Required for client configuration | Yes | Yes | Required for client configuration | Required for client configuration | No | Yes |
| L3 tool agent | Yes | Yes | Yes | Yes | Human review | Yes | Yes | Required for client configuration | Required for client configuration | Human review | Yes |
| L4 workflow agent | Yes | Yes | Yes | Yes | Human review | Yes | Yes | Required for client configuration | Required for client configuration | Human review | Yes |
| L5 multi-agent | Yes | Yes | Yes | Yes | Human review | Yes | Yes | Required for client configuration | Yes | Human review | Yes |
| L6 audited system | Yes | Yes | Yes | Yes | Human review | Yes | Yes | Required for client configuration | Yes | Human review | Yes |