SharePoint File Transfer Cowork plugin: upload files from any URL into SharePoint

June 10, 2026

What this plugin does

The SharePoint File Transfer Cowork plugin manages files across SharePoint from Copilot Cowork. Browse sites, document libraries, and folders. Upload files from public HTTPS URLs — small files upload inline, large files (250 MB+) stream in the background with resumable chunked uploads. Copy files and folders across sites and libraries with no size limit. Move and rename items within a library, create folders, set metadata columns, and generate sharing links.

The plugin is backed by a .NET MCP server deployed to Azure Container Apps with Microsoft Entra SSO and On-Behalf-Of (OBO) token exchange for Microsoft Graph.

Key capabilities

• Browse any SharePoint site, library, and folder the signed-in user has access to
• Upload files from any publicly reachable HTTPS URL (GitHub releases, CDN links, public downloads) into any SharePoint library the user can write to
• Copy files and folders across sites and libraries — copy_item uses Graph’s native async copy, so there’s no file size limit and no download/re-upload
• Move / rename items within the same document library
• Create folders, set metadata columns, and generate sharing links
• Resume or cancel large in-flight uploads

Full source: GitHub repository

Architecture

The runtime flow is straightforward:

Copilot Cowork ──SSO token──▶ Azure Container App (MCP server)
                                 │
                                 ├─ OBO exchange ──▶ Microsoft Graph (SharePoint)
                                 └─ Managed Identity ──▶ Azure Table Storage (session tracking)

The SSO token from Cowork gets exchanged via OBO for a Graph token scoped to SharePoint. Upload sessions are tracked in Azure Table Storage so large chunked uploads can resume after failures.

MCP tools

The plugin exposes 15 tools covering the full file lifecycle:

That tool surface covers four workflow patterns: browse and discover, upload and transfer, copy across sites, and organize and share.

Current limitations

• Move is same-drive only. move_item moves items within a single document library. For cross-library or cross-site moves, use copy_item followed by deleting the original (not yet automated as a single tool).

Why resumable uploads matter

Graph’s simple upload endpoint caps out at 250 MB. For anything larger, you need a chunked upload session. The plugin handles that automatically — upload_from_url picks the right strategy based on file size, and start_upload_session gives you explicit control when you need it.

If a large upload fails mid-stream, resume_upload_from_url picks up where it left off. get_upload_status lets you monitor progress without polling the MCP server directly.

Cross-site copy with no size limit

The copy_item tool uses Graph’s native async copy operation. The file never downloads to the MCP server and re-uploads — Graph handles the copy server-side. That means no file size limit and no timeout risk for large files. Use check_copy_status to monitor progress on long-running copies.

Deploy to Azure

The deployment uses Azure Developer CLI (azd) and Bicep templates:

1. Create the Entra app registration

Register a multi-tenant app in Microsoft Entra ID with these delegated Microsoft Graph permissions (admin consent required):

• Sites.ReadWrite.All
• Files.ReadWrite.All
• Sites.Read.All
• User.Read

Expose an API scope (for example, access_as_user) and note the Application ID URI.

2. Provision and deploy

azd init
azd provision
azd deploy

This creates a resource group, Azure Container Registry, Container Apps environment with a container app, Azure Storage account with an uploadSessions table, Application Insights, and RBAC assignments for ACR pull and Table Data Contributor.

3. Configure OBO credentials

After deployment, add the OBO client ID and secret to the container app:

CA_NAME="<container-app-name>"
RG_NAME="<resource-group-name>"

# Add the client secret as a Container App secret
az containerapp secret set -n $CA_NAME -g $RG_NAME \
  --secrets obo-client-secret="<your-client-secret>"

# Set environment variables
az containerapp update -n $CA_NAME -g $RG_NAME \
  --set-env-vars \
    OBO_CLIENT_ID="<your-client-id>" \
    OBO_CLIENT_SECRET=secretref:obo-client-secret

Use secretref: for the client secret — plain-text env vars get overwritten by azd deploy.

4. Register the Cowork plugin

1. Update manifest.json — replace ``, <YOUR-CONTAINER-APP-FQDN>, and <YOUR-OAUTH-REFERENCE-ID>
2. Package: Compress-Archive -Path manifest.json, color.png, outline.png, skills -DestinationPath "SharePoint File Transfer.zip"
3. Upload the .zip in M365 Admin Center > Settings > Integrated apps > Upload custom apps
4. Grant admin consent when prompted

Project structure

├── azure.yaml              # azd service definition
├── manifest.json           # Cowork plugin manifest
├── color.png               # Plugin icon (color)
├── outline.png             # Plugin icon (outline)
├── infra/                  # Bicep infrastructure-as-code
│   ├── main.bicep
│   ├── main.parameters.json
│   └── modules/
├── server/                 # .NET MCP server
│   ├── Program.cs
│   ├── Dockerfile
│   ├── Auth/               # SSO + OBO token exchange
│   ├── Endpoints/          # MCP JSON-RPC endpoint
│   ├── Graph/              # Graph client, upload runner, session store
│   └── Tools/              # MCP tool implementations
└── skills/                 # Cowork agent skill definitions

Why this pattern is useful

Moving files into SharePoint is a surprisingly common workflow step. Reports land on external portals, vendors share files via download links, data pipelines produce artifacts at public endpoints. Today those files get downloaded to a laptop, then manually uploaded to SharePoint.

This plugin lets Copilot handle that transfer server-side. The file streams directly from the source URL into SharePoint through the MCP server — it never touches the user’s machine. That’s faster, works for large files, and leaves an audit trail in SharePoint.

The cross-site copy capability fills another gap. Reorganizing files across SharePoint sites normally means downloading and re-uploading. With copy_item, Graph handles the copy natively — no data leaves Microsoft’s infrastructure.

The resumable upload pattern also makes this viable for production workloads where network reliability isn’t guaranteed.

Resources

• SharePoint File Transfer Cowork plugin
• SharingIsCaring repository
• Copilot Cowork plugin development
• Plugin authentication
• Microsoft Graph DriveItem upload