update_note · Obsidian MCP: Risk & Policy

WHAT IT DOES

What update_note does on Obsidian

AI agents use update_note to create or update resources in Obsidian — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Obsidian environment.

WHY IT NEEDS A POLICY

Why update_note needs a policy

This tool modifies existing notes by overwriting their content. While this is a Write operation (reversible via undo/version history in Obsidian), it poses a medium severity risk if misused by an agent—it could corrupt or replace important vault content. It does not delete data (which would be Destructive), but rather modifies it, placing it firmly in the Write category.

From the tool's definition Tool name 'update_note' with description 'Overwrite a note' indicates modification of existing data. The word 'Overwrite' suggests replacing content, which is a reversible write operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_note Rate-limited

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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "update_note": {
      "limits": [
        {
          "counter": "update_note_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Obsidian, so you can run agents against it safely.

FAQ

Questions about update_note

What does the update_note tool do? +

Overwrite a note. It is categorised as a Write tool in the Obsidian MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_note? +

Register the Obsidian 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 Obsidian. Nothing to install.

What risk level is update_note? +

update_note is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit update_note? +

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.

How do I block update_note completely? +

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.

What MCP server provides update_note? +

update_note is provided by the Obsidian MCP server (yanxue06/obsidian-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.