# message_participants

Send one private message to several participants of a course, as the participants page's "Send a message" does: to users (aliases) or userIds, or to everyone chosen by role, group or inactiveSince (everyone when none is given), the person left out. Returns who got it and who Moodle didn't write to, and why. The text is plain, with no aliases in it. Sent as the person, visibly: confirm the text and the recipients with the person first.

Agent View of the PolicyLayer registry record for `message_participants`. HTML page: https://policylayer.com/tools/falkenslab-moodle-mcp/message-participants

## Facts

- Tool: `message_participants`
- Server: Moodle (`@falkenslab/moodle-mcp`) — https://policylayer.com/tools/falkenslab-moodle-mcp.md
- Install: `npx -y @falkenslab/moodle-mcp`
- Homepage: https://www.npmjs.com/package/@falkenslab/moodle-mcp
- Risk category: Write (Medium risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 7 (2 required)
- Recommended policy verdict: Rate-limited

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `role` | integer | no | Or: everyone with this role |
| `text` | string | yes |  |
| `group` | integer | no | Or: everyone in this group |
| `users` | array | no | The participants' aliases, as the reading tools give them when the server pseudonymizes |
| `userIds` | array | no | The participants' user ids, when the server shows names |
| `courseId` | integer | yes |  |
| `inactiveSince` | string | no | Or: everyone who hasn't accessed the course since this date (ISO 8601) |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "message_participants",
    "arguments": {
      "text": "<text>",
      "courseId": 0
    }
  }
}
```

## Why message_participants is rated Medium

An AI agent can call message_participants 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.

## Use case

AI agents use message_participants 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.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Moodle:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "message_participants": {
      "limits": [
        {
          "counter": "message_participants_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Moodle (232)

- `delete_activity` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-activity.md
- `delete_book_chapter` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-book-chapter.md
- `delete_database_entry` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-database-entry.md
- `delete_database_field` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-database-field.md
- `delete_event` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-event.md
- `delete_feedback_item` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-feedback-item.md
- `delete_feedback_template` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-feedback-template.md
- `delete_glossary_entry` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-glossary-entry.md
- `delete_grade_category` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-grade-category.md
- `delete_grade_item` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-grade-item.md
- `delete_group` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-group.md
- `delete_grouping` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-grouping.md
- `delete_lesson_page` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-lesson-page.md
- `delete_post` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-post.md
- `delete_question_category` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-question-category.md
- `delete_questions` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-questions.md
- `delete_section` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-section.md
- `delete_workshop_example` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/delete-workshop-example.md
- `override_workshop_grade` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/override-workshop-grade.md
- `remove_quiz_slot` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/remove-quiz-slot.md
- `remove_site` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/remove-site.md
- `remove_workshop_reviewer` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/remove-workshop-reviewer.md
- `reset_course` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/reset-course.md
- `unenrol_user` — Destructive — https://policylayer.com/tools/falkenslab-moodle-mcp/unenrol-user.md
- `browser_navigate` — Execute — https://policylayer.com/tools/falkenslab-moodle-mcp/browser-navigate.md
- `browser_wait` — Execute — https://policylayer.com/tools/falkenslab-moodle-mcp/browser-wait.md
- `enrol_users` — Execute — https://policylayer.com/tools/falkenslab-moodle-mcp/enrol-users.md
- `grade_forum_user` — Execute — https://policylayer.com/tools/falkenslab-moodle-mcp/grade-forum-user.md
- `rate` — Execute — https://policylayer.com/tools/falkenslab-moodle-mcp/rate.md
- `start_quiz_attempt` — Execute — https://policylayer.com/tools/falkenslab-moodle-mcp/start-quiz-attempt.md
- …and 202 more: https://policylayer.com/tools/falkenslab-moodle-mcp.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=falkenslab-moodle-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/falkenslab-moodle-mcp