AI agents call list_npcs 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 and displays existing NPC data without creating, modifying, deleting, or executing any operations. It is a pure read operation with minimal security risk—the only concern would be unauthorized access to campaign information, but the tool itself cannot cause harm when misused by an AI agent.
From the tool's definition Tool name 'list_npcs' and description 'List all NPCs in the current campaign' indicate a query/retrieval operation with no modification or execution of external actions.
Documented attack patterns abuse exactly the kind of access list_npcs 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 list_npcs:
{
"version": "1",
"default": "deny",
"tools": {
"list_npcs": {}
}
}list_npcs is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
List all NPCs in the current campaign. 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 list_npcs: 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.
list_npcs 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 list_npcs 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 list_npcs. 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.
list_npcs 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.
Free to start. No card required.
30 D&D MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.