The excellent vector database Pinecone has a very useful API, but client support is sparse. While the API and its clients are in theory based off of an OpenAPI spec, no one seems to be able to find it.
But I needed an OpenAPI spec for the API, so I reverse engineered one (read: copy and pasted from the documentation).
It is very new and so should be considered very experimental. If you use it and find a bug, please open an issue, or even better submit a pull request!