AI agents invoke start_combat to trigger actions in DMCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool executes game logic and state transitions that have in-game consequences. While not destructive (combat can be undone in an RPG context) and not financial, it initiates procedural operations whose outcomes depend on runtime parameters. This makes it Execute rather than Write.
From the tool's definition Tool performs 'Initialize a combat encounter' which triggers external game state operations and execution of combat mechanics whose effects depend on provided arguments (encounter parameters, participant selection, etc.).
Documented attack patterns abuse exactly the kind of access start_combat gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and DMCP, and nothing reaches the server without passing your rules. This is the rule we recommend for start_combat:
{
"version": "1",
"default": "deny",
"tools": {
"start_combat": {
"limits": [
{
"counter": "start_combat_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}start_combat stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Initialize a combat encounter. It is categorised as a Execute tool in the DMCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the D MCP server in PolicyLayer and add a rule for start_combat: 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 DMCP. Nothing to install.
start_combat is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the start_combat 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 start_combat. 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.
start_combat is provided by the D MCP server (shawnrushefsky/dmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from DMCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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204 DMCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.