mcp-open-api

Turns an OpenAPI spec into a slot of an mcp-broker, validated by a human before it is published, then governed by the broker like any other provider.

OpenAPI spec ──> mcp-open-api (slot "designer") ──> Tier 4 page ──publish──> slot definition (JSON)
                       │                               │                            │
                       └── pushes its page into the    └── operator's own token     └── run by the broker:
                           broker's static mount           + checks re-run by           authorize, audit, limits,
                                                           the broker                   traceparent, secrets kept

Converting OpenAPI to MCP is not new. A 300-operation spec does not make a good slot, though: operations have to be chosen, renamed, described for an LLM, narrowed with fixed parameters, and tied to a capability and a resource path. That design work is what this project is about, and what makes a REST API safe to hand to an agent.

How it works

• A provider, not a broker feature. mcp-open-api registers on the broker as an ordinary provider, on the slot designer. Its MCP tools import a spec, propose tools, tune them, validate and try them. An agent can drive them.

• A human publishes. A transformation becomes a published slot only after a Tier 4 operator validates it, on a web page that mcp-open-api pushes into the broker's static mount. The operator signs in with their own token, reviews the checks and the diff, approves each write tool one by one, and publishes. The broker re-runs every check and audits the publication under the operator's name. The provider itself holds no publishing right.

• The page can be a slot. While validating, the page can publish itself as a temporary slot (preview-<slot>-<id>) exposing the transformed tools, so they can be called for real before publication. Calls are relayed to the broker; API secrets never reach the browser.

• The output is declarative. A published slot is a slot definition: one readable, diffable JSON file with no secret in it. The broker runs it without generated code and without an extra process. Every call goes through the broker's declared authorization, audit, execution limits and W3C trace propagation, and the target API's credentials stay in the broker's security file.

Related MCP server: MCP Flow

Status

Design stage. The package is scaffolded; no feature is implemented yet. The design covers the slot definition format, the declarative runtime and its governance in the broker, the broker's admin routes and pushed static pages, mcp-open-api itself, the temporary preview slot, and the future MCP path for agents.

Requirements

• Node.js 20.11 or later.

• An mcp-broker, 1.6.1 or later. Publishing slots and pushed pages need broker features that are not released yet.

Development

npm install
npm run build
npm test

License

Apache-2.0. See LICENSE.