AI agents call get_user_kv to retrieve information from Lanyard without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only reads and queries data from the Lanyard API. It retrieves pre-stored KV data associated with a user's Discord presence without creating, modifying, deleting, or executing any operations.
From the tool's definition The tool 'get_user_kv' retrieves custom key-value data for a Discord user. The description explicitly states 'Get...custom data', indicating a data retrieval operation with no modification or side effects.
Attacks that exploit this kind of access
Get Lanyard KV (key-value) custom data for a Discord user - provide Discord user ID. It is categorised as a Read tool in the Lanyard MCP Server, which means it retrieves data without modifying state.
Register the Lanyard MCP server in PolicyLayer and add a rule for get_user_kv: 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 Lanyard. Nothing to install.
get_user_kv 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_kv 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_kv. 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_kv is provided by the Lanyard MCP server (nntin/lanyard-mcp-server). 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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