Migrating from Manual Cursor API Prompts to Spec-Driven Tools

Short answer: Stop paying an agent to re-derive the API from pasted notes. Put the OpenAPI file in the repo, generate the tools and mock from it, and let the agent read the current contract every session. The migration is incremental: establish the contract, wire the tools, then retire the prompt notes as the agent proves it works.

What the manual pattern costs

Pasting curl commands and endpoint notes into the chat is a per-session tax. The agent re-reads, re-derives, and re-types the same facts, and any stale note becomes a confident error. The knowledge lives in the conversation, not in a maintained artifact.

The migration in stages

1. Establish the contract: convert the existing requests and notes into an OpenAPI file kept in the repo.
2. Generate the surface: compile the spec into an MCP server and a mock.
3. Run in parallel: let the agent use the tools while keeping the notes as a fallback.
4. Retire the notes: once the call log shows correct calls, stop pasting them.

How to judge success

The clearest signal is the call log: the agent selects the right tools, supplies typed arguments, and the responses verify against the contract. When that is consistent, the manual notes are redundant.

The discipline that keeps it working

The contract is the source of truth. When the API changes, change the spec first; the tools and mock regenerate, and the agent is never reading a stale description.

This is part of the Powerduck vs Cursor comparison. Finish with why they are better together.