Copilot Studio Agent Tool Not Detecting File Input from Power Automate Flow

Nuwan Theekshana 0 Reputation points
2026-10-05T03:53:48.36+00:00

Hi everyone,

I'm facing an issue with Copilot Studio and Power Automate Agent Flows.

I created a flow using "When an agent calls the workflow" with the following inputs:

  • RequestPayload (Text)
  • AttachmentFiles (File)

The flow saves successfully and the File input is visible in Power Automate.

However, when I add the flow as a Tool in Copilot Studio, only the text input is detected:

  • RequestPayload

 

The File input (AttachmentFiles) does not appear in the Tool Inputs section.

 

What I've tried:

  • Removed and re-added the tool
  • Refreshed the tool schema
  • Created a brand-new V2 flow
  • Changed the File input name multiple times (AttachmentFiles, UploadedFiles, FuelAttachments, etc.)
  • Saved and republished the agent
  • Removed and re-added the flow multiple times

The result is always the same. Only the Text input is exposed in Copilot Studio.

Additionally, if I manually try to add an input named "AttachmentFiles" in the Tool configuration, Copilot Studio returns:

"There is an error: 'DuplicateItem'"

This makes it seem like Copilot Studio recognizes the input internally, but it is not rendering or exposing it in the Tool UI.

Questions:

  1. Are File/File Collection inputs currently supported for Agent Tools in Copilot Studio?
  2. Has anyone successfully passed uploaded files from an Agent to a Power Automate flow using Tool inputs?
  3. Is this a known limitation or a bug?
  4. Is there a recommended workaround for sending PDF/JPG attachments to a flow from an Agent?

Any guidance would be greatly appreciated.

Thank you.

Microsoft Copilot | Other
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  1. Ashlesha Pawar (Tata Consultancy Services Limited) 480 Reputation points Microsoft External Staff
    2026-10-05T05:28:36.99+00:00

    Thanks for the detailed repro. I checked the current Microsoft Copilot Studio documentation, and File inputs are supported for Power Automate/agent flows used as tools. Microsoft currently documents passing a user file to a flow tool using the System.Activity.Attachments context and mapping the file content and name through Power Fx Custom values. Therefore, this does not appear to be a general limitation that File inputs are unsupported.

    The documented pattern is to map the attachment content and name using:

    First(System.Activity.Attachments).Content

    and

    First(System.Activity.Attachments).Name

    File inputs must be configured using a Custom Power Fx value rather than “Dynamically fill with AI.”

    In your case, however, the fact that the File parameter is completely missing from the Tool Inputs UI while manually adding the same parameter returns DuplicateItem is not the expected documented experience. This may indicate that the File parameter exists in the underlying tool schema but is not being rendered correctly in the current Copilot Studio experience.

    There have also been recent community reports of similar File-input/tool-panel behavior in the newer Copilot Studio experience.

    As a next step, we recommend testing with a minimal flow containing only a Text input, a File input, and a Respond to the agent action, then publishing it and adding it as a tool. Please also provide the Copilot Studio UX/version, environment region, screenshots of the trigger input configuration and Tool Inputs panel, and the full DuplicateItem error details.

    If the File input is still absent in that minimal repro while the backend reports it as a duplicate when manually added, we can investigate this as a potential Copilot Studio tool-schema/UI issue rather than a limitation of File inputs.

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