obsidian_set_property · Obsidian MCP: Risk & Policy

WHAT IT DOES

What obsidian_set_property does on Obsidian

AI agents use obsidian_set_property 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_set_property needs a policy

This tool modifies note metadata by setting or creating frontmatter properties. While modifications are reversible (can be edited/removed), the operation creates or overwrites structured data. This is clearly a Write operation rather than Read (it modifies rather than just retrieves). It is not Destructive because the changes are reversible and do not permanently delete data.

From the tool's definition Tool description states it 'Sets a frontmatter property on a note' and 'Creates the frontmatter block if missing.' The frontmatter property setting is a modification operation that alters note metadata reversibly.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

obsidian_set_property Rate-limited

obsidian_set_property 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_set_property": {
      "limits": [
        {
          "counter": "obsidian_set_property_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_set_property

What does the obsidian_set_property tool do? +

Sets a frontmatter property on a note. Creates the frontmatter block if missing. 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_set_property? +

Register the Obsidian MCP server in PolicyLayer and add a rule for obsidian_set_property: 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_set_property? +

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

Can I rate-limit obsidian_set_property? +

Yes. Add a rate_limit block to the obsidian_set_property 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_set_property completely? +

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

obsidian_set_property 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.