append_content · Obsidian Modified MCP: Risk & Policy

WHAT IT DOES

What append_content does on Obsidian Modified

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

WHY IT NEEDS A POLICY

Why append_content needs a policy

This tool appends data to an existing file or creates a new file if absent. It modifies data but is generally reversible (content can be removed or file deleted), making it a Write operation. Misuse could bloat or corrupt notes, hence medium severity.

From the tool's definition Append content to a file. Creates the file if it does not exist.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

append_content Rate-limited

append_content 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": {
    "append_content": {
      "limits": [
        {
          "counter": "append_content_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 Modified, so you can run agents against it safely.

FAQ

Questions about append_content

What does the append_content tool do? +

Append content to a file. Creates the file if it does not exist. It is categorised as a Write tool in the Obsidian Modified MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on append_content? +

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

What risk level is append_content? +

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

Can I rate-limit append_content? +

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

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

append_content is provided by the Obsidian Modified MCP server (@marwansaab/obsidian-modified-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.