Qt C++ Code Review
x-tools-author/x-tools
Read-only review of Qt6 C++ code that combines a deterministic lint script with six parallel analysis agents and reports only high-confidence issues.
A skill your agent uses when a Firefox preference has to be remotely controllable: putting a new feature behind a pref so it can be experimented on, rolled out gradually, or disabled remotely via…
Install Nimbus Prefs
$ npx skills add mozilla-firefox/firefox --skill nimbus-prefs -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install mozilla-firefox/firefox nimbus-prefs --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/nimbus-prefs .claude/skills/nimbus-prefs && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "nimbus-prefs" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/nimbus-prefs into .claude/skills/nimbus-prefs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "nimbus-prefs", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/nimbus-prefsType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add mozilla-firefox/firefox --skill nimbus-prefs -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install mozilla-firefox/firefox nimbus-prefs --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/nimbus-prefs .agents/skills/nimbus-prefs && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "nimbus-prefs" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/nimbus-prefs into .agents/skills/nimbus-prefs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "nimbus-prefs", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add mozilla-firefox/firefox --skill nimbus-prefs -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install mozilla-firefox/firefox nimbus-prefs --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/nimbus-prefs .cursor/skills/nimbus-prefs && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "nimbus-prefs" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/nimbus-prefs into .cursor/skills/nimbus-prefs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "nimbus-prefs", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/mozilla-firefox/firefox.git --path .agents/skills/nimbus-prefs--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add mozilla-firefox/firefox --skill nimbus-prefs -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install mozilla-firefox/firefox nimbus-prefs --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/nimbus-prefs .gemini/skills/nimbus-prefs && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "nimbus-prefs" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/nimbus-prefs into .gemini/skills/nimbus-prefs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "nimbus-prefs", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install mozilla-firefox/firefox nimbus-prefsInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add mozilla-firefox/firefox --skill nimbus-prefs -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/nimbus-prefs .github/skills/nimbus-prefs && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "nimbus-prefs" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/nimbus-prefs into .github/skills/nimbus-prefs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "nimbus-prefs", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add mozilla-firefox/firefox --skill nimbus-prefs -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install mozilla-firefox/firefox nimbus-prefs --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/nimbus-prefs .opencode/skills/nimbus-prefs && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "nimbus-prefs" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/nimbus-prefs into .opencode/skills/nimbus-prefs/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "nimbus-prefs", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
nimbus-prefs- GitHub stars
- 13k
- Token cost
- ~6k tokens
- SKILL.md length
- 2,900 words
- Files
- 1
- Skills in repo
- 7
- Repo updated
- First seen
- Licence
- Custom licence
At a glance
A skill your agent uses when a Firefox preference has to be remotely controllable: putting a new feature behind a pref so it can be experimented on, rolled out gradually, or disabled remotely via…
- Works in 5 steps: declare the pref → add the Nimbus feature → read the value → …
- A Firefox preference has to be remotely controllable: putting a new feature behind a pref so it can be experimented on
- SKILL.md covers Goal, Pick a mechanism, Step 1 — declare the pref and Step 2 — add the Nimbus feature, plus 9 more sections
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
Nimbus Prefs is an agent skill from mozilla-firefox/firefox. Use this skill when a Firefox preference has to be remotely controllable: putting a new feature behind a pref so it can be experimented on, rolled out gradually, or disabled remotely via Nimbus. Covers declaring prefs (StaticPrefList.yaml, firefox.js), adding a feature to toolkit/components/nimbus/FeatureManifest.yaml, choosing between fallbackPref and setPref, reading values from JS and C++, recording exposure events, and pairing the pref with Glean telemetry. Trigger on "put this behind a pref", "make this…
Its SKILL.md is about 6k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
It sits in Development. It works with C++. The repository describes itself as: The official repository of Mozilla's Firefox web browser.
When your agent uses it
- A Firefox preference has to be remotely controllable: putting a new feature behind a pref so it can be experimented on
- Rolled out gradually
- Disabled remotely via Nimbus
- Put this behind a pref
Example prompts
- “put this behind a pref”
- “make this Nimbus-controllable”
- “add a feature gate”
- “/nimbus-prefs”
Workflow steps
5 steps, taken from the step headings in SKILL.md.
- declare the pref
- add the Nimbus feature
- read the value
- record exposure
- pair it with Glean
What it can do on your machine
Read from SKILL.md and the folder at commit 59c8a94. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are javascript, yaml and bash).
From the folder's file list and the shell code blocks in SKILL.md.
Network
Links to these hosts (documentation or services it may open):
experimenter.info
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Nimbus Prefs loads about 6k tokens when it runs. Until then it costs about 158 tokens; SKILL.md has 2,900 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 2,900 words (~5,958 tokens).
“For background on Nimbus itself — experiment design, the Experimenter console, analysis — see experimenter.info. This skill covers the in-tree side.”
- name
- nimbus-prefs
Files
Just SKILL.md in .agents/skills/nimbus-prefs of mozilla-firefox/firefox.
Open the folder on GitHubat commit 59c8a94
Compare with similar skills
Nimbus Prefs next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Nimbus Prefs this skillmozilla-firefox/firefox | 13k | — | ~6k | Automated safety check: Pass | Custom licence | |
| Qt C++ Code Reviewx-tools-author/x-tools | 1.1k | 2 repos | ~4.3k | Automated safety check: Pass | BSD-3-Clause | |
| YugabyteDB ASH Instrumentationyugabyte/yugabyte-db | 11k | — | ~4.5k | Automated safety check: Pass | Custom licence | |
| pybind11 Release Preparationpybind/pybind11 | 18k | — | ~1.7k | Automated safety check: Pass | Custom licence | |
| Qt Cpp ReviewSerial-Studio/Serial-Studio | 7.2k | — | ~4.3k | Automated safety check: Pass | Custom licence | |
| Paddle Eager GraphPaddlePaddle/Paddle | 24k | — | ~562 | Automated safety check: Pass | Apache-2.0 |
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Related
Works with
Categories
Questions about Nimbus Prefs
What does Nimbus Prefs do?
A skill your agent uses when a Firefox preference has to be remotely controllable: putting a new feature behind a pref so it can be experimented on, rolled out gradually, or disabled remotely via…. Nimbus Prefs is an agent skill from mozilla-firefox/firefox. Use this skill when a Firefox preference has to be remotely controllable: putting a new feature behind a pref so it can be experimented on, rolled out gradually, or disabled remotely via Nimbus.
When should I use Nimbus Prefs?
Nimbus Prefs fits situations like: A Firefox preference has to be remotely controllable: putting a new feature behind a pref so it can be experimented on; rolled out gradually; disabled remotely via Nimbus; put this behind a pref.
How do I install Nimbus Prefs in Claude Code?
Run `npx skills add mozilla-firefox/firefox --skill nimbus-prefs -a claude-code`. Or copy the skill folder (.agents/skills/nimbus-prefs in mozilla-firefox/firefox) into .claude/skills/nimbus-prefs in your project. Claude Code loads it when a task matches its description.
How do I install Nimbus Prefs in Codex?
Run `npx skills add mozilla-firefox/firefox --skill nimbus-prefs -a codex`. Or copy the skill folder (.agents/skills/nimbus-prefs in mozilla-firefox/firefox) into .agents/skills/nimbus-prefs in your project. Codex loads it when a task matches its description.
Can I use Nimbus Prefs in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add mozilla-firefox/firefox --skill nimbus-prefs -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/nimbus-prefs, .gemini/skills/nimbus-prefs, .github/skills/nimbus-prefs and .opencode/skills/nimbus-prefs in your project.
What does Nimbus Prefs need to run?
SKILL.md names no scripts, command-line tools or credentials: Nimbus Prefs is instructions for the agent only.
Does Nimbus Prefs access the network?
SKILL.md names 1 domain. As links in the text: experimenter.info. This is read from the text; nothing was executed.
Is Nimbus Prefs safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Nimbus Prefs use?
Nimbus Prefs has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.
How many tokens does Nimbus Prefs use?
About 6k tokens (SKILL.md is roughly 24k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Nimbus Prefs?
Skills that share tags, products or a category with Nimbus Prefs: Qt C++ Code Review (x-tools-author/x-tools, 1.1k stars), YugabyteDB ASH Instrumentation (yugabyte/yugabyte-db, 11k stars), pybind11 Release Preparation (pybind/pybind11, 18k stars) and Qt Cpp Review (Serial-Studio/Serial-Studio, 7.2k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Nimbus Prefs?
mozilla-firefox (a GitHub organization) maintains it in mozilla-firefox/firefox, which has 13,384 GitHub stars. The repository holds 7 skills in this directory. The repository was last updated on October 8, 2026.
Source: mozilla-firefox/firefox on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.