Update the title, content, type, or tags of an existing note.
AI agents use zk_update_note to create or update resources in Zettelkasten — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Zettelkasten environment.
The tool modifies existing notes by updating their attributes (title, content, type, tags), which is a reversible write operation. It does not delete data (ruling out Destructive), execute code (ruling out Execute), move money (ruling out Financial), or merely retrieve data (ruling out Read).
From the tool's definition Tool description states it 'Update[s] the title, content, type, or tags of an existing note.' This modifies data reversibly (updates rather than deletes).
Documented attack patterns abuse exactly the kind of access zk_update_note gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Zettelkasten, and nothing reaches the server without passing your rules. This is the rule we recommend for zk_update_note:
{
"version": "1",
"default": "deny",
"tools": {
"zk_update_note": {
"limits": [
{
"counter": "zk_update_note_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}zk_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.
Free to start. No card required.
Update the title, content, type, or tags of an existing note. It is categorised as a Write tool in the Zettelkasten MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Zettelkasten MCP server in PolicyLayer and add a rule for zk_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 Zettelkasten. Nothing to install.
zk_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 zk_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 zk_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.
zk_update_note is provided by the Zettelkasten MCP server (liam-deacon/zettelkasten-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Zettelkasten, 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.
14 Zettelkasten tools catalogued and risk-classified — across an index of 43,000+ MCP servers.