update_frontmatter

THE RISK

Medium Risk

Why update_frontmatter needs a policy

This tool modifies note frontmatter (YAML metadata) in a reversible manner. While it changes data, the operation is not destructive—frontmatter can be re-edited or reverted. It does not execute code, move money, or permanently delete data.

From the tool's definition Tool description states 'Merge new key-value pairs into a note' — a direct modification operation. Tool name 'update_frontmatter' indicates structural metadata changes to note files.

Documented attack patterns abuse exactly the kind of access update_frontmatter gives an agent:

POLICY

How to control update_frontmatter

PolicyLayer is an MCP gateway — it sits between your AI agents and Obsidian Mcp Pro, and nothing reaches the server without passing your rules. This is the rule we recommend for update_frontmatter:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "update_frontmatter": {
      "limits": [
        {
          "counter": "update_frontmatter_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

update_frontmatter 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.

Create a free account and register Obsidian Mcp Pro — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Obsidian Mcp Pro tools

Destructive delete_note Delete a note. By default the file is moved to the vault Execute index_vault Build or refresh the embedding index used by Execute query_base Run a Base file Write append_to_note Append text to the end of an existing note without altering prior content. By default, ins Write prepend_to_note Insert content at the top of an existing note Write add_canvas_edge Create a directed edge connecting two existing canvas nodes. Both fromNode and toNode must Write add_canvas_node Add a new node to an Obsidian canvas and persist the updated file. Supports four node type Write create_daily_note Create a daily note for today (or a specific date) in the vault

All 41 Obsidian Mcp Pro tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about update_frontmatter

What does the update_frontmatter tool do? +

Merge new key-value pairs into a note. It is categorised as a Write tool in the Obsidian Mcp Pro MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_frontmatter? +

Register the Obsidian Mcp Pro MCP server in PolicyLayer and add a rule for update_frontmatter: 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 Mcp Pro. Nothing to install.

What risk level is update_frontmatter? +

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

Can I rate-limit update_frontmatter? +

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

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

update_frontmatter is provided by the Obsidian Mcp Pro MCP server (rps321321/obsidian-mcp-pro). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Obsidian Mcp Pro tool call.

Start from Obsidian Mcp Pro, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →