Create a new note or overwrite an existing note with content.
AI agents use write_note to create or update resources in MCP Notes — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MCP Notes environment.
This tool creates or modifies note data, which is characteristic of Write operations. Although overwriting could affect existing content, notes in a personal knowledge management system are typically recoverable from backups or version history, making this reversible rather than permanently destructive.
From the tool's definition Tool description states 'Create a new note or overwrite an existing note with content.' The capability to both create and overwrite indicates reversible modification of data.
Documented attack patterns abuse exactly the kind of access write_note gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Notes, and nothing reaches the server without passing your rules. This is the rule we recommend for write_note:
{
"version": "1",
"default": "deny",
"tools": {
"write_note": {
"limits": [
{
"counter": "write_note_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}write_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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Create a new note or overwrite an existing note with content. It is categorised as a Write tool in the MCP Notes MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the MCP Notes MCP server in PolicyLayer and add a rule for write_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 MCP Notes. Nothing to install.
write_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 write_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 write_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.
write_note is provided by the MCP Notes MCP server (markacianfrani/mcp-notes). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Notes, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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9 MCP Notes tools catalogued and risk-classified — across an index of 43,000+ MCP servers.