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You already document your internal APIs with OpenAPI. API Servers lets HasteKit consume that spec directly: register the server once, and every operation in the spec becomes a tool your agents can call. No MCP server to write, no glue code.
API Servers

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Registering an API server

  1. Open Agent Framework → API Servers (or attach a new one inline from the agent’s Tools tab).
  2. Provide:
  1. Save. HasteKit parses the spec; every operation becomes an available tool with the parameters and response schema described by the spec.

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What gets generated

For each operation:
  • Tool name — derived from operationId (falling back to method + path).
  • Description — from the operation’s summary / description.
  • Parameters — path params, query params, and request body are all flattened into the tool’s input schema. Required vs optional is preserved.
  • Response — returned to the agent as a JSON object (or string for non-JSON responses).
Schema fidelity is high — oneOf, enum, format hints, and required fields are all preserved on the tool input schema, so the model’s tool call is constrained the same way a typed client would be.

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Attaching to an agent

  1. Open the agent → Tools tab → API Servers section.
  2. Select the registered server.
  3. Optionally filter which operations are exposed (you rarely want all 200 of an internal API).
  4. Optionally flag specific operations as Requires Approval (gates mutating calls behind a human) or Deferred (keeps them out of the prompt until the agent asks).
  5. Save.

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When to use API Servers vs alternatives