Reserve quota and return presigned B2 PUT URLs. For files <100MB you get one URL; for larger files you get a multipart description (parts[]). The returned file row sits in pending_upload status until drive_upload_complete confirms B2 received the bytes.
AI agents use drive_upload_initiate to create or update resources in TrekMail MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your TrekMail MCP Server environment.
This tool creates new file entries and reserves storage quota, making it a Write operation (creates or modifies data reversibly). Severity is medium because misuse could waste storage quota, create unwanted file entries, or fill disk space, but the file is only pending until completion—actual persistence requires a follow-up call. The presigned URL mechanism limits direct control to authorized B2 operations.
From the tool's definition Tool initiates file uploads by reserving quota and returning presigned URLs; creates a pending file row in the system.
Attacks that exploit this kind of access
Reserve quota and return presigned B2 PUT URLs. For files <100MB you get one URL; for larger files you get a multipart description (parts[]). The returned file row sits in pending_upload status until drive_upload_complete confirms B2 received the bytes. It is categorised as a Write tool in the TrekMail MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the TrekMail MCP Server MCP server in PolicyLayer and add a rule for drive_upload_initiate: 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 TrekMail MCP Server. Nothing to install.
drive_upload_initiate is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the drive_upload_initiate 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 drive_upload_initiate. 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.
drive_upload_initiate is provided by the TrekMail MCP Server MCP server (trekmail/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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Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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