AI agents call search_course_users 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 or queries user information within a course context. It performs a search operation without modifying, deleting, or executing actions. The blast radius is minimal—it only exposes existing user roster data that course participants typically have access to view. This is a standard read operation consistent with LMS functionality.
From the tool's definition Tool name 'search_course_users' and description 'Search for users in a course' indicate a query/lookup operation with no modification or deletion of data.
Documented attack patterns abuse exactly the kind of access search_course_users 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 search_course_users:
{
"version": "1",
"default": "deny",
"tools": {
"search_course_users": {}
}
}search_course_users is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Search for users in a course. 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 search_course_users: 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.
search_course_users 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 search_course_users 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 search_course_users. 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.
search_course_users is provided by the Canvas MCP Server MCP server (plyght/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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30 Canvas MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.