AI agents use update_note to create or update resources in DMCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your DMCP environment.
This tool creates or modifies data without permanent deletion or irreversible consequences. In the context of an RPG dungeon master system, updating notes is a typical write operation for managing game state and narrative details. The blast radius is minimal—incorrect note updates can be corrected by subsequent updates. This does not execute external code, delete data, or involve financial transactions.
From the tool's definition Tool name 'update_note' and description 'Update a note' indicate modification of existing data (a note) in a reversible manner.
Documented attack patterns abuse exactly the kind of access update_note 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 update_note:
{
"version": "1",
"default": "deny",
"tools": {
"update_note": {
"limits": [
{
"counter": "update_note_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update_note stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Update a note. It is categorised as a Write tool in the DMCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the D MCP server in PolicyLayer and add a rule for update_note: 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.
update_note is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the update_note 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 update_note. 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.
update_note 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.
Free to start. No card required.
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