download-bytes
Download binary content from Microsoft Graph and return it as base64. Single tool for any binary read: drive file content, mail attachment, profile photo, Teams hosted content, meeting recording. Returns { contentType, encoding: "base64", contentLength, contentBytes }. For large drive/SharePoint ...
This record as markdown: /tools/jo3zik-ms-365-mcp-server/download-bytes.md
What download-bytes does on Ms 365
AI agents call download-bytes 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 |
Parameters from the server's own tool schema.
Why download-bytes is rated Low
Even though download-bytes 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 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, this is the rule to start with:
download-bytes 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 call is checked against it from then on.
Questions about download-bytes
Download binary content from Microsoft Graph and return it as base64. Single tool for any binary read: drive file content, mail attachment, profile photo, Teams hosted content, meeting recording. Returns { contentType, encoding: "base64", contentLength, contentBytes }. For large drive/SharePoint file content, prefer get-download-url, which returns a pre-authenticated URL to stream bytes out-of-band instead of base64 through the agent context. It is categorised as a Read tool in the Ms 365 MCP Server, which means it retrieves data without modifying state.
download-bytes accepts 1 parameter: target. Required: target. 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: 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 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 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. 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 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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