# Capability

> A Capability is a declared, invocable action an origin can perform or vouch for. It is the origin's offer to do work, not just to display content.

A named, described and specified function an origin exposes for invocation, with defined inputs, outputs and provenance. Capability is what an origin can do. Content is only what it can show.

## Why it matters

- Capability over content. In an agentic internet the useful unit is an action an agent can take, not a paragraph it must read.
- Declaring capabilities explicitly, in JSON, llms.txt and an MCP manifest, makes an origin discoverable and usable by machines without bespoke integration.
- A capability is a promise. Backing it with provenance is what makes the promise trustworthy rather than merely available.

## Examples

- ask. Resolve a question against the corpus and return a cited answer.
- definitions. Return a canonical definition and its relationships.
- provenance. Return the verifiable source of a claim.
- research. Expose a body of work for retrieval and reasoning.

## Not this

- A page that describes what an origin could do, with no invocable surface behind it.
- Capabilities without declared inputs or outputs, so only a human reading docs can use them.

## Related

invocation, provenance, origin

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id: capability · version: 0.1 · status: draft · source: https://heliacon.com/research/definitions/capability/