Download the actual content of a file attached to a submission. Returns file content as base64 for binary files or as text for text files.
AI agents call download-submission-file to retrieve information from Canvas MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and returns submission file content without altering or deleting it, making it a Read operation. Severity is medium rather than low because it accesses student submission data, which may contain sensitive academic or personal information; an AI agent with unconstrained access could exfiltrate submission files from courses it should not access, but the tool itself does not modify, delete, or…
From the tool's definition Tool name 'download-submission-file' and description 'Download the actual content of a file attached to a submission. Returns file content as base64 for binary files or as text for text files.' indicate data retrieval with no modification.
Documented attack patterns abuse exactly the kind of access download-submission-file gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Canvas MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for download-submission-file:
{
"version": "1",
"default": "deny",
"tools": {
"download-submission-file": {}
}
}download-submission-file is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Download the actual content of a file attached to a submission. Returns file content as base64 for binary files or as text for text files. It is categorised as a Read tool in the Canvas MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Canvas MCP Server MCP server in PolicyLayer and add a rule for download-submission-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 Canvas MCP Server. Nothing to install.
download-submission-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-submission-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-submission-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-submission-file is provided by the Canvas MCP Server MCP server (r-huijts/canvas-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Canvas MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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50 Canvas MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.