AI agents call list_characters 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/queries campaign character data without creating, modifying, deleting, or executing any operations. It is a straightforward read operation with minimal risk if misused by an AI agent, as it only returns existing information.
From the tool's definition Tool name 'list_characters' and description 'List all characters in the current campaign' indicate retrieval of data with no modification or side effects.
Documented attack patterns abuse exactly the kind of access list_characters 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_characters:
{
"version": "1",
"default": "deny",
"tools": {
"list_characters": {}
}
}list_characters is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List all characters 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_characters: 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_characters 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_characters 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_characters. 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_characters 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.