What is CHP?
An open protocol that makes every capability a person, agent, product, or system exposes governable and tamper-evidently provable.
The Capability Host Protocol (CHP) is the open protocol for making the actions that agents, tools, and systems take governed, provable, and replayable — on one signed record, at the moment they happen.
When something runs through CHP, the boundary it crosses produces structured, tamper-evident evidence on a single plane: what was attempted, what happened, and what governed it — the policy, risk tier, safety check, human approval, and any denial — all signed together. A human approval, an agent's tool call, and a product's API call become the same kind of governed, provable event. That one governed, signed plane is the difference: observability tools split execution across separate unsigned signals and carry no governance; CHP unifies and proves both.
The five-minute mental model
CHP turns what can be done into something that can be:
| Step | Meaning |
|---|---|
| Declared | A capability has a stable id, version, and described behavior. |
| Invoked | A caller crosses the boundary with a correlation context and payload. |
| Governed | Before it runs, a fixed pipeline — policy, invariants, authority, autonomy, safety — can allow, condition, or deny the invocation. |
| Evidenced | Every attempt emits an event: started, completed, failed, denied, or skipped. |
| Correlated | One correlation id ties the whole session together, across hosts. |
| Replayed | Ask for the ordered evidence of any correlation id — locally, no backend. |
Where to start
- Govern your agents — the boundary that is real today. One command captures every tool call as replayable evidence.
- Core concepts — capability, host, invocation, evidence, correlation, denial, conformance.
- The spec and schemas — the normative contract and wire format.
What CHP is not
CHP is deliberately narrow. It is not a model provider, an agent framework, a workflow engine, or a policy vendor — and it does not replace MCP, OpenTelemetry, or your application's authorization. It standardizes one boundary: how capabilities are declared, called, governed, and proven.