Download an attachment and return it as base64-encoded data.
AI agents call download_attachment to retrieve information from Bluebubbles without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool reads and retrieves existing attachment data from iMessage conversations. While it accesses private message content, the action is non-destructive and non-modifying. Downloading/reading attachments is a Read operation. Severity is low because attachment access is limited to data that already exists on the user's BlueBubbles server, with no capability to modify, execute, or delete data.
From the tool's definition Tool performs 'download' operation which retrieves attachment data and returns it as base64-encoded data. No modification, deletion, or execution of code occurs. The operation is a data retrieval with no side effects.
Attacks that exploit this kind of access
Download an attachment and return it as base64-encoded data. It is categorised as a Read tool in the Bluebubbles MCP Server, which means it retrieves data without modifying state.
Register the Bluebubbles MCP server in PolicyLayer and add a rule for download_attachment: 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 Bluebubbles. Nothing to install.
download_attachment 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_attachment 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_attachment. 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_attachment is provided by the Bluebubbles MCP server (metaember/bluebubbles-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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