UAIX, MCP, and webhooks answer different questions. UAIX records the validated exchange and evidence boundary. MCP connects a model client to tools, resources, prompts, or application context. Webhooks deliver event notifications between systems.
Quick chooser
| Need | Use | Reason |
|---|---|---|
| Portable public record, release evidence, validation, provenance, trust, or conformance. | UAIX / UAI-1 | The output needs to be reviewed, cited, replayed, or attached to a support claim. |
| Tool, resource, or prompt access inside a model-client session. | MCP | The session needs runtime access, not necessarily a durable public evidence packet. |
| One system notifying another that an event happened. | Webhook | The main requirement is event delivery, not a full standards envelope. |
| Runtime action plus public evidence. | Use together | Let the runtime/tool/event layer do the work, then export the reviewable boundary as UAI-1 evidence. |
Capability-adaptive rule
A client may use MCP tools or receive webhook events and still publish a UAIX capability profile. The profile should say which level the client actually supports, what fallback applies, what consent is required, and what evidence must travel.