download-bytes-to-file
Write authenticated Microsoft Graph byte content to a local file on the server, returning { path, contentType, bytesWritten } instead of base64. The only out-of-band way to save mail attachments and meeting recordings, whose bytes are exposed solely through authenticated endpoints. Also handles p...
This record as markdown: /tools/jo3zik-ms-365-mcp-server/download-bytes-to-file.md
What download-bytes-to-file does on Ms 365
AI agents call download-bytes-to-file to retrieve information from Ms 365 without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
target | string | Yes | Relative Microsoft Graph path starting with "/". Common paths: /drives/{drive-id}/items/{driveItem-id}/content (drive file content); /me/messages/{message-id}/a |
outputPath | string | Yes | Absolute path on the server's filesystem where the bytes are written, e.g. /Users/me/downloads/invoice.pdf. Must be absolute; relative paths are rejected. The p |
Parameters from the server's own tool schema.
Why download-bytes-to-file is rated Low
Even though download-bytes-to-file only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Attacks that exploit this kind of access
The rule that runs download-bytes-to-file safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Ms 365, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For download-bytes-to-file, this is the rule to start with:
download-bytes-to-file is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Ms 365, apply this rule, and every download-bytes-to-file call is checked against it from then on.
Questions about download-bytes-to-file
Write authenticated Microsoft Graph byte content to a local file on the server, returning { path, contentType, bytesWritten } instead of base64. The only out-of-band way to save mail attachments and meeting recordings, whose bytes are exposed solely through authenticated endpoints. Also handles profile photos and Teams hosted content. Writes to an absolute outputPath and never overwrites an existing file. stdio mode only: not available over HTTP. For OneDrive or SharePoint file content, get-download-url is preferred — it returns a pre-authenticated URL for fully out-of-band download without the server fetching the bytes. It is categorised as a Read tool in the Ms 365 MCP Server, which means it retrieves data without modifying state.
download-bytes-to-file accepts 2 parameters: target, outputPath. Required: target, outputPath. The full parameter table on this page comes from the server's own tool schema.
Register the Ms 365 MCP server in PolicyLayer and add a rule for download-bytes-to-file: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Ms 365. Nothing to install.
download-bytes-to-file is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the download-bytes-to-file rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for download-bytes-to-file. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
download-bytes-to-file is provided by the Ms 365 MCP server (@jo3zik/ms-365-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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