List endpoints and schemas
Concrete endpoints and request/response shapes anchor the contract before any implementation begins.
API SPEC PROMPT
API Contract Prompt Builder
Specify endpoints, schemas, error handling, authentication, and backward compatibility needs to build a complete API contract prompt for AI-assisted development.
- Uses your inputs in a transparent calculation
- Instant result with practical next steps
- No signup required
Planning guidance only. Validate important decisions with customer evidence and your delivery team.
YOUR INPUTS
Build your result
Complete every field. The result updates only when you choose Calculate.
How it works
Define error handling
A consistent error shape and status code convention prevents an agent from inventing a different one per endpoint.
Add auth and compatibility needs
Authentication method and versioning strategy round out a contract an agent can implement without guessing.
Continue learning: API-first development with AI agents
Frequently asked questions
Why write the contract before the implementation prompt?
A contract-first approach gives a coding agent (or a human reviewer) something concrete to check the implementation against, instead of inferring the API shape after the fact.
What if I don't know the exact schema yet?
Fill in what you do know — field names, rough types — and mark uncertain parts explicitly rather than leaving the section blank; a rough schema still beats an agent guessing from nothing.
Does this generate an OpenAPI spec?
No — it produces a structured plain-language contract summary meant to go into a prompt. You can still formalize it as OpenAPI/Swagger separately if needed.
How is completeness scored?
Each of the four sections is checked for at least 10 characters of real content; the score is the percentage of sections that pass.
How We Compare
| Feature | MVPHub | Postman | Swagger / OpenAPI |
|---|---|---|---|
| Structured 4-section prompt draft | Included | Not included | Not included |
| Completeness scoring | Included | Not included | Not included |
| No account required | Included | Not included | Included |
| Plain-language draft usable before a formal spec exists | Included | Not included | Not included |
Postman and OpenAPI tooling validate and test a formal spec once it exists. This tool helps you draft the plain-language contract prompt that comes before that, for handing to a coding agent.
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