write_note · Obsidian Nexus MCP: Risk & Policy

WHAT IT DOES

What write_note does on Obsidian Nexus

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

WHY IT NEEDS A POLICY

Why write_note needs a policy

This tool creates or modifies markdown notes in an Obsidian vault. The operation is reversible (notes can be edited or deleted), so it falls under Write rather than Destructive.

From the tool's definition Tool description states 'Write or update a note in the Obsidian vault'; verb 'write or update' indicates reversible creation/modification of data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

write_note Rate-limited

write_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": {
    "write_note": {
      "limits": [
        {
          "counter": "write_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 Nexus, so you can run agents against it safely.

FAQ

Questions about write_note

What does the write_note tool do? +

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

How do I enforce a policy on write_note? +

Register the Obsidian Nexus MCP server in PolicyLayer and add a rule for write_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 Nexus. Nothing to install.

What risk level is write_note? +

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

Can I rate-limit write_note? +

Yes. Add a rate_limit block to the write_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 write_note completely? +

Set action: deny in the PolicyLayer policy for write_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 write_note? +

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