What is umbraco-extension-reviewer?

A review agent for Umbraco code, running after Umbraco skills finish. It checks whether the result follows recommended practices and Umbraco’s design.

Use it to review Umbraco customisations after they have been generated.

It provides a follow-up check for code generated by other Umbraco skills.

umbraco-extension-reviewer — Agent for Claude Code by umbraco

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo

git clone --depth 1 https://github.com/umbraco/Umbraco-CMS-Backoffice-Skills

Made for: Claude Code.

Or install umbraco-cms-backoffice-skills, the plugin that ships this one along with the rest of its 67 skills, 1 agent.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/agents/umbraco/umbraco-cms-backoffice-skills/umbraco-extension-reviewer/github.svg)](https://agentmods.dev/agents/umbraco/umbraco-cms-backoffice-skills/umbraco-extension-reviewer)

Your own site

<a href="https://agentmods.dev/agents/umbraco/umbraco-cms-backoffice-skills/umbraco-extension-reviewer"><img src="https://agentmods.dev/badge/agents/umbraco/umbraco-cms-backoffice-skills/umbraco-extension-reviewer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/agents/umbraco/umbraco-cms-backoffice-skills/umbraco-extension-reviewer"><img src="https://agentmods.dev/badge/agents/umbraco/umbraco-cms-backoffice-skills/umbraco-extension-reviewer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 51 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 510 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin unknown No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00051	$0.00510
Opus 5.5	$0.00020	$0.00204
Sonnet 5.5	$0.00010	$0.00102
Haiku 4.5	$0.00005	$0.00051

Measured 2mo ago against content hash 616a2cd1d0ed, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

umbraco-extension-reviewer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/umbraco-backoffice-skills/agents/umbraco-extension-reviewer.md · 76 lines

The source is not reproduced here

No licence file

Read it on GitHub

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 76 lines · 51 tokens per session scan A 616a2cd1d0ed

Subscribe to this mod's changes

umbraco-extension-reviewer is an agent published in the GitHub repository umbraco/Umbraco-CMS-Backoffice-Skills (27 stars, last pushed 1mo ago), with no licence file. It adds 51 tokens to every session and 510 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Code review

umbraco-extension-reviewer next to 6 agents from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
umbraco-extension-reviewerumbraco/Umbraco-CMS-Backoffice-Skills	Agent	27	1mo ago	none	A	51	Claude Code
thermo-nuclear-code-quality-review-subagentmichael-denyer/pstack-claude	Agent	4.2k	today	MIT	A	68	Claude Code
review-obsidian-guidelinesuphy/obsidian-reminder	Agent	662	4d ago	MIT	A	63	Claude Code
karimo-implementeropensesh/KARIMO	Agent	291	28d ago	Apache-2.0	A	49	Claude Code
atomic-auditordamusix/atomic-claude	Agent	116	today	MIT	A	169	Claude Code
reviewergenkovich/sdd	Agent	202	25d ago	MIT	A	81	Claude Code
Reviewermonkilabs/opencastle	Agent	80	4d ago	MIT	A	30	Claude Code