append_to_note · Obsidian MCP: Risk & Policy

WHAT IT DOES

What append_to_note does on Obsidian

AI agents use append_to_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 append_to_note needs a policy

This tool writes data to an Obsidian vault by appending markdown content to notes. It is reversible (content can be removed), placing it in the Write category. Misuse could pollute notes with unwanted content or create unintended notes, giving it medium severity.

From the tool's definition 'Append markdown to the end of an existing note. Creates the note if it doesn't exist' — modifies existing notes by appending content, or creates new notes

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

append_to_note Rate-limited

append_to_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": {
    "append_to_note": {
      "limits": [
        {
          "counter": "append_to_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 append_to_note

What does the append_to_note tool do? +

Append markdown to the end of an existing note. Creates the note if it doesn. 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 append_to_note? +

Register the Obsidian MCP server in PolicyLayer and add a rule for append_to_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 append_to_note? +

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

Can I rate-limit append_to_note? +

Yes. Add a rate_limit block to the append_to_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 append_to_note completely? +

Set action: deny in the PolicyLayer policy for append_to_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 append_to_note? +

append_to_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.