AI agents call get_user_subreddits to retrieve information from PersonalizationMCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves personal subscription data from Reddit but does not modify, execute, or delete anything. However, it accesses sensitive personal information (user's Reddit subscription preferences), which could expose behavioral patterns or interests if misused by an AI agent without proper consent — hence 'medium' severity rather than 'low'.
From the tool's definition Tool name and description indicate it 'Get user's subscribed subreddits' — a data retrieval operation with no modification or execution capability. The verb 'Get' and the query nature (listing subscribed subreddits) are characteristic of Read operations.
Documented attack patterns abuse exactly the kind of access get_user_subreddits gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and PersonalizationMCP, and nothing reaches the server without passing your rules. This is the rule we recommend for get_user_subreddits:
{
"version": "1",
"default": "deny",
"tools": {
"get_user_subreddits": {}
}
}get_user_subreddits is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get user's subscribed subreddits. It is categorised as a Read tool in the PersonalizationMCP MCP Server, which means it retrieves data without modifying state.
Register the Personalization MCP server in PolicyLayer and add a rule for get_user_subreddits: 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 PersonalizationMCP. Nothing to install.
get_user_subreddits 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 get_user_subreddits 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 get_user_subreddits. 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.
get_user_subreddits is provided by the Personalization MCP server (yangliangwei/personalizationmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 88 PersonalizationMCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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88 PersonalizationMCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.