obsidian_append_to_file

THE RISK

Medium Risk

Why obsidian_append_to_file needs a policy

This tool adds content to files (creating new ones or appending to existing ones). It is a write operation — reversible in principle (content can be removed) and does not delete or overwrite existing data. Misuse could pollute vault files with unwanted content, hence medium severity.

From the tool's definition Append content to a new or existing file in the vault

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

POLICY

How to control obsidian_append_to_file

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

policy.json

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

obsidian_append_to_file 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 Advanced Obsidian MCP Server — 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 Advanced Obsidian MCP Server tools

Destructive obsidian_delete_file Delete a file or directory from your vault Execute obsidian_execute_commands Execute one or more commands in obsidian interface Execute obsidian_open_files Open one or more files in the vault in a new leaf Write obsidian_patch_file Insert content into an existing note relative to a heading, block reference, or frontmatte Write obsidian_put_file Create a new file in your vault or update the content of an existing one Read obsidian_batch_get_files Return the contents and metadata of one or more notes (.md files) in your vault Read obsidian_complex_search Complex search for documents using a JsonLogic query with support for 'glob' and 'regexp' Read obsidian_get_active_note Get the content and metadata of the currently active note in Obsidian

All 16 Advanced Obsidian MCP Server tools →

Write tools on other servers

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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 obsidian_append_to_file

What does the obsidian_append_to_file tool do? +

Append content to a new or existing file in the vault. It is categorised as a Write tool in the Advanced Obsidian MCP Server 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_to_file? +

Register the Advanced Obsidian MCP Server MCP server in PolicyLayer and add a rule for obsidian_append_to_file: 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 Advanced Obsidian MCP Server. Nothing to install.

What risk level is obsidian_append_to_file? +

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

Can I rate-limit obsidian_append_to_file? +

Yes. Add a rate_limit block to the obsidian_append_to_file 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_to_file completely? +

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

obsidian_append_to_file is provided by the Advanced Obsidian MCP Server MCP server (tokidoo/mcp-obsidian-advanced). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Advanced Obsidian MCP Server tool call.

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

CHECK YOUR STACK →