reply_to_post
Reply to a post in a Moodle forum discussion, with optional attachments (local files). The subject defaults to Moodle's "Re: …". Returns the new post's id and its discussion. Posts as the person, visibly: confirm the text with the person first.
This record as markdown: /tools/falkenslab-moodle-mcp/reply-to-post.md
What reply_to_post does on Moodle
AI agents use reply_to_post to create or update resources in Moodle, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Moodle environment.
| Parameter | Type | Required | Description |
|---|---|---|---|
embed | array | — | Absolute local files (images…) to embed in the HTML, which names each by its file name: <img src="shot.png"> |
files | array | — | Absolute local paths to attach |
fields | object | — | Other post form fields by name, e.g. {"pinned": true} for a teacher |
postId | integer | Yes | The post to reply to, as get_discussion gives it |
message | string | Yes | The message (HTML); no aliases in it, since people read it |
subject | string | — | |
subscribe | boolean | — | Subscribe to the discussion; Moodle's default when missing |
Parameters from the server's own tool schema.
Why reply_to_post is rated Medium
An AI agent can call reply_to_post faster than any human can review: one bad instruction and it creates or modifies resources in Moodle by the hundred, each call as confident as the last.
Attacks that exploit this kind of access
The rule that runs reply_to_post safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Moodle, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For reply_to_post, this is the rule to start with:
reply_to_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.
The button opens the PolicyLayer dashboard: create your workspace, connect Moodle, apply this rule, and every reply_to_post call is checked against it from then on.
Questions about reply_to_post
Reply to a post in a Moodle forum discussion, with optional attachments (local files). The subject defaults to Moodle's "Re: …". Returns the new post's id and its discussion. Posts as the person, visibly: confirm the text with the person first. It is categorised as a Write tool in the Moodle MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
reply_to_post accepts 7 parameters: embed, files, fields, postId, message, subject, subscribe. Required: postId, message. The full parameter table on this page comes from the server's own tool schema.
Register the Moodle MCP server in PolicyLayer and add a rule for reply_to_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 Moodle. Nothing to install.
reply_to_post is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the reply_to_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.
Set action: deny in the PolicyLayer policy for reply_to_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.
reply_to_post is provided by the Moodle MCP server (@falkenslab/moodle-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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