AI agents call get_npc to retrieve information from D&D 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 NPC (Non-Player Character) data from a D&D campaign management system. The verb 'get' combined with 'information' clearly indicates a query operation that returns data without altering state, creating side effects, or enabling external operations. There is no destructive, financial, or code execution capability.
From the tool's definition Tool name 'get_npc' and description 'Get NPC information' indicate retrieval of data without modification or side effects.
Documented attack patterns abuse exactly the kind of access get_npc gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and D&D MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for get_npc:
{
"version": "1",
"default": "deny",
"tools": {
"get_npc": {}
}
}get_npc is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get NPC information. It is categorised as a Read tool in the D&D MCP Server MCP Server, which means it retrieves data without modifying state.
Register the D&D MCP Server MCP server in PolicyLayer and add a rule for get_npc: 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 D&D MCP Server. Nothing to install.
get_npc 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_npc 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_npc. 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_npc is provided by the D&D MCP Server MCP server (study-flamingo/gamemaster-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from D&D 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 D&D MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.