discourse_create_post · Discourse MCP: Risk & Policy

WHAT IT DOES

What discourse_create_post does on Discourse MCP

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

WHY IT NEEDS A POLICY

Why discourse_create_post needs a policy

This tool creates new content (a post/reply) in a forum topic, which is a reversible write operation. It does not delete, execute arbitrary code, or move money. The medium severity reflects that an AI agent could spam posts, create offensive content, or flood a forum, but the damage is mitigatable through moderation and deletion. The 1 request/second rate limit provides some protection against abuse.

From the tool's definition Tool description states 'Create a new post (reply) in an existing topic' and explicitly requires 'write permissions'. The action is reversible (posts can be edited or deleted by moderators/admins).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

discourse_create_post Rate-limited

discourse_create_post 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": {
    "discourse_create_post": {
      "limits": [
        {
          "counter": "discourse_create_post_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 Discourse MCP, so you can run agents against it safely.

FAQ

Questions about discourse_create_post

What does the discourse_create_post tool do? +

Create a new post (reply) in an existing topic. Requires write permissions. Rate limited to 1 request per second. It is categorised as a Write tool in the Discourse MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on discourse_create_post? +

Register the Discourse MCP server in PolicyLayer and add a rule for discourse_create_post: 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 Discourse MCP. Nothing to install.

What risk level is discourse_create_post? +

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

Can I rate-limit discourse_create_post? +

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

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

discourse_create_post is provided by the Discourse MCP server (king-of-the-grackles/discourse-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.