Upload to signed URL
Receives a file at a one-time signed URL issued by the MCP request-media-upload-tool. No API key: the signature authorizes the request. Send the file as multipart/form-data in the media field, for example curl -F media=@launch.jpg "<upload_url>". The URL works once, until it expires (15 minutes by default); a second upload to it returns 409. The returned upload_token is then used as a media item, like a token from POST /uploads. Accepted files: JPEG, PNG, GIF and WebP images (HEIC and HEIF too when the server can convert them, stored as JPEG), MP4 and MOV videos, and PDF documents. Size caps: 10 MB per image (and at most about 67 megapixels, 8192 × 8192 pixels in total), 1 GB per video, 100 MB per PDF. Each network enforces its own, usually smaller, caps when the post is scheduled or published (GET /content-types). A file the server cannot read returns 422 with only message: Unable to read uploaded file.
Path Parameters
Upload token from the signed URL.
Query Parameters
Part of the signed URL.
Part of the signed URL (Unix timestamp).
Part of the signed URL.
Body
The file.

