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Use the staged upload flow for PDFs that exist on the local machine or workspace. CapOut MCP is hosted remotely, so it cannot read those files directly. This is an MCP-only workflow. It is separate from the public REST POST /upload API. Staged uploads support PDFs up to 50 MiB.

Rate limit

capout_create_upload_url is limited to 10 signed upload URLs per minute per authenticated API key. For folder runs, batch runs, or subagent-heavy flows, create at most 10 staged upload URLs at a time before requesting more.

Step 1: create a friendly upload URL

Typical response:
The MCP does not expose raw presigned S3 upload URLs here. It returns a short CapOut upload URL plus a ready-to-run curl_command.

Step 2: upload the PDF locally

Run the returned command on the same machine where the PDF exists:

Step 3: process the staged upload

Successful response:

What to do next

After capout_process_staged_upload succeeds, keep polling until completion with Status and Waiting.