create_comment · Langfuse MCP Server MCP: Risk & Policy

WHAT IT DOES

What create_comment does on Langfuse MCP Server

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

WHY IT NEEDS A POLICY

Why create_comment needs a policy

This tool creates new comments, which are metadata additions that can be modified or deleted later. While it modifies state in the Langfuse system, the operation is reversible and does not destroy data or execute arbitrary code.

From the tool's definition Tool name 'create_comment' and description 'Create a new comment' explicitly indicate creation of new data on traces, observations, sessions, or prompts—a reversible write operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_comment Rate-limited

create_comment 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": {
    "create_comment": {
      "limits": [
        {
          "counter": "create_comment_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 Langfuse MCP Server, so you can run agents against it safely.

FAQ

Questions about create_comment

What does the create_comment tool do? +

Create a new comment on traces, observations, sessions, or prompts. It is categorised as a Write tool in the Langfuse 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 create_comment? +

Register the Langfuse MCP Server MCP server in PolicyLayer and add a rule for create_comment: 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 Langfuse MCP Server. Nothing to install.

What risk level is create_comment? +

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

Can I rate-limit create_comment? +

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

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

create_comment is provided by the Langfuse MCP Server MCP server (therealsachin/langfuse-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.