update_note · Obsidian MCP Server MCP: Risk & Policy

WHAT IT DOES

What update_note does on Obsidian MCP Server

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

WHY IT NEEDS A POLICY

Why update_note needs a policy

This tool modifies existing notes in the Obsidian vault, making it a Write operation. It is not Destructive because updates are reversible (the previous version is overwritten but not permanently deleted in a way that cannot be undone through version history or backups). Severity is high because an AI agent could inadvertently overwrite important notes or knowledge base content, potentially causing loss of user work.

From the tool's definition Tool description states 'Update an existing note' and 'missing directories will be created automatically', indicating it modifies data in the vault. The description explicitly mentions updating notes, which is a reversible data modification 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 MCP Server, so you can run agents against it safely.

FAQ

Questions about update_note

What does the update_note tool do? +

Update an existing note in the Obsidian vault. If createIfNotExists is true, missing directories will be created automatically. If createIfNotExists is false and the file does not exist, the operation will FAIL. It is categorised as a Write tool in the Obsidian MCP Server 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 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 MCP Server. 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 MCP server (markheramis/obsidian-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.