Building and customizing solutions using Microsoft 365 Copilot APIs and tools
Microsoft supports uploading chat attachments for agents to read and summarize. However, it doesn't currently document a supported mechanism for passing the uploaded file's binary content and filename directly into a workflow tool.
For your meeting-minutes workflow, the most reliable workaround is to save the original transcript to SharePoint first, rather than uploading it through agent chat. Then use a SharePoint Get file content action to retrieve the transcript and pass it to an agent node for meeting-minutes generation. Microsoft documents this exact SharePoint-to-agent workflow pattern. As one verification check, upload a sample transcript to SharePoint and run this workflow to confirm that the agent generates minutes while the original file remains available.