MCP for Community Builder is a free add-on for MCP for J that lets your AI client look after a Community Builder site. Its 32 tools cover members and their profile fields, sign-up moderation, custom fields and profile tabs, connections, lists, CB's own plugins and configuration, plus an audit of your registration emails that catches a confirmation link that renders as nothing. You can ask who's waiting for approval, approve them, or add a field to the profile, all without opening the admin. Every change goes through Community Builder's own code, and no email goes out to a member unless you ask for it.
Why this exists
Community Builder runs a lot of quiet machinery behind a sign-up. Approval, email confirmation, generated passwords and the emails that carry them all depend on settings spread across several screens, and when one of them is off, the first you hear of it is a new member who can't get in. The add-on started with exactly that: a Pending email whose confirmation link came out empty, which is invisible from the admin and slow to track down by hand. Your AI client can read the whole picture at once, tell you which email CB will send at each step of a sign-up on your site, and work the moderation queue for you.
What Claude can do
There are 32 tools, grouped roughly the way you'd reach for them.
| Area | Tools | What you can do |
|---|---|---|
| Diagnostics | 4 | Get an overview with member counts by moderation state, run a health check (the same member checks as CB's own Check Users Database, plus field, install and moderation-backlog checks), and take a read-only, redacted look at CB's core tables. |
| Configuration | 3 | Run the registration audit, read CB's configuration, and change named settings while leaving the rest exactly as they were. |
| Members | 4 | List and search members by moderation state, read one member with every profile field grouped by tab, set profile field values, and see the moderation queue oldest first. |
| Moderation | 5 | Approve or reject a sign-up, confirm an email address on a member's behalf, ban or unban a profile, block or unblock a login, and read the reports members have made about each other. |
| Fields | 7 | List, read, create, change and delete profile fields, see which field types your install can create, and set a field's list of options. |
| Tabs | 5 | List, read, create, change and delete profile tabs. |
| Community | 4 | See connections between members, your member lists, and CB's own plugins, and publish or unpublish one of those plugins. |
Installing it
You'll need Joomla 5 or 6, PHP 8.2 or later, MCP for J, and Community Builder from Joomlapolis. The free Community Builder core is all this needs, and 2.12.0 is the version it was built and tested against.
- Open Components โ MCP for Joomla โ Browse MCP Add-Ons and click Install on this add-on. You can also download the ZIP above and install it through System โ Install โ Extensions.
- That's the whole install. The plugin switches itself on, and the tools show up in your AI client the next time it lists them.
There's no admin screen for this plugin, by design. It adds tools to MCP for J rather than a place to click.
Using it
Start with "Give me an overview of Community Builder", then "Run a health check", then "Audit my registration settings". The third one is the one to do even if sign-ups seem fine. It shows the Pending and Welcome emails as CB will actually render them, says which one goes out at each step for your settings, and flags the combinations that quietly break sign-up: a [CONFIRM] link that renders empty because email confirmation is off, confirmation switched on with no email to carry the link, generated passwords that no email delivers, and approvals that no moderator is told about.
After that, ask in plain language. "Who's waiting for approval?", "Show me Dana's profile" and "Add a Company field to the Contact Info tab" all work. A new field is left off the registration form unless you ask for it there, so it never turns up on your live sign-up page by surprise. If a member's confirmation email never arrived, "Confirm Dana's email for her" does what the Confirmed toggle in CB's user list does.
Community Builder doesn't run under Joomla's API as it ships. Approving a member there would store the approval and unblock the account, then fail before the welcome email. So every call here runs CB inside its own back-end context, which is the setting its moderation code was written for, and writes go through CB's own table classes so its events fire and the Joomla account and the CB profile stay in step. Every write reads both back afterwards and reports what changed.
A few things CB does that are worth knowing:
- Deleting a field deletes every member's answer. CB drops the field's database column, even though a comment in its own code says the data is kept.
delete_cb_fieldshows you how many members have a value and won't go ahead withoutconfirm_data_loss. - Members store an option's text, not its id. Renaming or removing an option leaves every member who chose it holding a value that no longer exists, so the option tool counts them and refuses unless you tell it that's what you want.
- A ban hides the profile but doesn't stop the member logging in. Blocking is the separate tool for that.
- The first CB save of a user created outside CB can leave them looking unactivated in Joomla. The profile tool creates the CB profile row the way CB's Synchronize Users does first, so that doesn't happen.
Creating and deleting members, and changing usernames, email addresses, passwords and user groups, are left to MCP for J's own user tools. CB's system plugin cleans up its profile rows when a Joomla user is deleted.
Emails are held back unless you ask
Approving, rejecting, confirming, banning and unbanning all make Community Builder email the member. Through these tools, none of those emails is sent unless you pass send_email: true. Every email CB would have sent comes back in the response exactly as CB built it, so you can read it first and then repeat the call with the email switched on. Under Joomla's API, CB would also build every link in those emails pointing into the REST API rather than your site, so the links are rewritten to your site's address before anything goes out.
There's one case where holding the email back isn't safe. With CB's Generate Registration Passwords setting on, approving or confirming a member replaces their password with a new random one, and the welcome email is the only thing that carries it. Approve quietly and the member is left with a password nobody knows. So in that case the approve and confirm tools refuse unless send_email is true.
Permissions and security
The tools follow Community Builder's own access rules, checked for the person whose MCP connection makes each request. Working with members needs access to Joomla's Users manager, moderating them also needs permission to change their state, and only a Super User can moderate a Super User. Fields, tabs, lists, plugins and the diagnostics follow the matching sections of CB's admin.
Some things are never handed back: Joomla passwords and activation data, CB's email confirmation code (masked in returned emails too, since whoever has it can confirm the account), registration IP addresses, CB password-type fields, the settings of CB's plugins, and the Joomlapolis install-from-web key and token. Passwords CB generates are masked in the returned emails as well. The table reader refuses CB's session table and the private-message tables outright.
Why it's free
Community Builder core is free and GPL-licensed, and this add-on works with the core, so it's free for the same reason. Joomlapolis also sells add-ons for it, such as CB Paid Subscriptions, GroupJive and CB Gallery. None of those are covered here, and the table reader only reaches the tables CB core creates. If you rely on one of them and would like tools for it, let me know.
This is version 1.0.0. It was built against Community Builder 2.12.0 and every one of the 32 tools was driven live on Joomla 6.2, with each write checked in the database afterwards. That testing caught several bugs, which were fixed before release. The one path not yet tried live is a real sign-up from the front end, so the emails CB sends at the moment someone registers were checked against CB's source rather than an actual registration. If you run the registration audit on your own site, I'd like to hear what it finds.
Open source
GPL-2.0-or-later, the same license as Joomla itself. Source lives on GitHub.
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