prepend · Obsidian Local MCP: Risk & Policy

WHAT IT DOES

What prepend does on Obsidian Local

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

WHY IT NEEDS A POLICY

Why prepend needs a policy

This tool modifies an existing note by inserting content at the beginning. It is a reversible write operation (content can be removed), not destructive. Misuse could corrupt note content but has limited blast radius confined to the targeted note.

From the tool's definition Prepend content to the beginning of a note

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

prepend Rate-limited

prepend 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": {
    "prepend": {
      "limits": [
        {
          "counter": "prepend_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 Local, so you can run agents against it safely.

FAQ

Questions about prepend

What does the prepend tool do? +

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

How do I enforce a policy on prepend? +

Register the Obsidian Local MCP server in PolicyLayer and add a rule for prepend: 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 Local. Nothing to install.

What risk level is prepend? +

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

Can I rate-limit prepend? +

Yes. Add a rate_limit block to the prepend 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 prepend completely? +

Set action: deny in the PolicyLayer policy for prepend. 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 prepend? +

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