Developed comprehensive OpenAPI documentation and an interactive Swagger UI for the Hasher-Matcher-Actioner API within the facebook/ThreatExchange repository. Leveraged Python, Flask, and the flask-openapi3 library to define clear API schemas and response models, ensuring that API contracts were explicit and integration points well-documented. This work enhanced the developer experience by providing accessible, interactive documentation, which streamlined onboarding and facilitated faster, more reliable integration for users of the HMA API. The documentation was closely linked to specific code commits for traceability, reflecting a methodical approach to maintainability and transparency. No major bug fixes were addressed during this period.