obsidian_append_note · Obsidian MCP: Risk & Policy

WHAT IT DOES

What obsidian_append_note does on Obsidian

AI agents use obsidian_append_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 obsidian_append_note needs a policy

This tool modifies an existing note by adding content to it. It is reversible in principle (the appended content could be removed), so it falls under Write rather than Destructive. Misuse could corrupt or pollute notes with unwanted content, giving it medium severity.

From the tool's definition Appends markdown content to the end of an existing note

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

obsidian_append_note Rate-limited

obsidian_append_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": {
    "obsidian_append_note": {
      "limits": [
        {
          "counter": "obsidian_append_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 obsidian_append_note

What does the obsidian_append_note tool do? +

Appends markdown content to the end of an existing 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 obsidian_append_note? +

Register the Obsidian MCP server in PolicyLayer and add a rule for obsidian_append_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 obsidian_append_note? +

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

Can I rate-limit obsidian_append_note? +

Yes. Add a rate_limit block to the obsidian_append_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 obsidian_append_note completely? +

Set action: deny in the PolicyLayer policy for obsidian_append_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 obsidian_append_note? +

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