Begin a chunked audio upload for large payloads. Returns upload_id and max_chunk_bytes (~60KB).
AI agents use transcribe_upload_start to create or update resources in Video Toolkit — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Video Toolkit environment.
This tool initiates an upload session, which creates a new resource (upload session) on the server. While the data being uploaded (audio for transcription) is not inherently sensitive in this context, the tool modifies server state by creating an upload session. This is a Write operation rather than Read (which would only retrieve data).
From the tool's definition Tool description states 'Begin a chunked audio upload' — this explicitly indicates creating/initiating a write operation (starting an upload session).
Attacks that exploit this kind of access
Begin a chunked audio upload for large payloads. Returns upload_id and max_chunk_bytes (~60KB). It is categorised as a Write tool in the Video Toolkit MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Video Toolkit MCP server in PolicyLayer and add a rule for transcribe_upload_start: 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 Video Toolkit. Nothing to install.
transcribe_upload_start 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 transcribe_upload_start 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 transcribe_upload_start. 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.
transcribe_upload_start is provided by the Video Toolkit MCP server (jamesanz/transcript-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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