MCP Server Builder
anthropics/skills
Guides the design and implementation of Model Context Protocol servers in TypeScript or Python, from tool naming and error messages to evaluation.
Show console errors and failed network requests. An agent skill from mozilla/firefox-devtools-mcp.
Custom licenceAuto-check passed
Install Debug
$ npx skills add mozilla/firefox-devtools-mcp --skill debug -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install mozilla/firefox-devtools-mcp debug --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-devtools-mcp.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/firefox-devtools-mcp/skills/debug .claude/skills/debug && 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 "debug" agent skill from https://github.com/mozilla/firefox-devtools-mcp/tree/main/plugins/firefox-devtools-mcp/skills/debug into .claude/skills/debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "debug", 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-devtools-mcp/tree/main/plugins/firefox-devtools-mcp/skills/debugType 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-devtools-mcp --skill debug -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install mozilla/firefox-devtools-mcp debug --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla/firefox-devtools-mcp.git skills-src && mkdir -p .agents/skills && cp -r skills-src/plugins/firefox-devtools-mcp/skills/debug .agents/skills/debug && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "debug" agent skill from https://github.com/mozilla/firefox-devtools-mcp/tree/main/plugins/firefox-devtools-mcp/skills/debug into .agents/skills/debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "debug", 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-devtools-mcp --skill debug -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install mozilla/firefox-devtools-mcp debug --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla/firefox-devtools-mcp.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/plugins/firefox-devtools-mcp/skills/debug .cursor/skills/debug && 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 "debug" agent skill from https://github.com/mozilla/firefox-devtools-mcp/tree/main/plugins/firefox-devtools-mcp/skills/debug into .cursor/skills/debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "debug", 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-devtools-mcp.git --path plugins/firefox-devtools-mcp/skills/debug--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-devtools-mcp --skill debug -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install mozilla/firefox-devtools-mcp debug --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla/firefox-devtools-mcp.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/plugins/firefox-devtools-mcp/skills/debug .gemini/skills/debug && 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 "debug" agent skill from https://github.com/mozilla/firefox-devtools-mcp/tree/main/plugins/firefox-devtools-mcp/skills/debug into .gemini/skills/debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "debug", 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-devtools-mcp debugInstalls 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-devtools-mcp --skill debug -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/mozilla/firefox-devtools-mcp.git skills-src && mkdir -p .github/skills && cp -r skills-src/plugins/firefox-devtools-mcp/skills/debug .github/skills/debug && 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 "debug" agent skill from https://github.com/mozilla/firefox-devtools-mcp/tree/main/plugins/firefox-devtools-mcp/skills/debug into .github/skills/debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "debug", 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-devtools-mcp --skill debug -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-devtools-mcp debug --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla/firefox-devtools-mcp.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/plugins/firefox-devtools-mcp/skills/debug .opencode/skills/debug && 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 "debug" agent skill from https://github.com/mozilla/firefox-devtools-mcp/tree/main/plugins/firefox-devtools-mcp/skills/debug into .opencode/skills/debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "debug", 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
debug- GitHub stars
- 468
- Token cost
- ~241 tokens
- SKILL.md length
- 58 words
- Files
- 1
- Skills in repo
- 6
- Repo updated
- First seen
- Licence
- Custom licence
At a glance
Show console errors and failed network requests. An agent skill from mozilla/firefox-devtools-mcp.
- SKILL.md covers Usage, Examples and What Happens
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
What it does
Debug is an agent skill from mozilla/firefox-devtools-mcp. Show console errors and failed network requests
Its SKILL.md is about 240 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
It works with Model Context Protocol. The repository describes itself as: Model Context Protocol server for Firefox DevTools - enables AI assistants to inspect and control Firefox browser through WebDriver BiDi.
Example prompts
- “/debug”
What it can do on your machine
Read from SKILL.md and the folder at commit 5c69888. 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.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
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
Debug loads about 241 tokens when it runs. Until then it costs about 13 tokens; SKILL.md has 58 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 58 words (~241 tokens).
“Displays debugging information from the current page.”
- name
- debug
- argument-hint
- console|network|all
- disable-model-invocation
- true
Files
Just SKILL.md in plugins/firefox-devtools-mcp/skills/debug of mozilla/firefox-devtools-mcp.
Open the folder on GitHubat commit 5c69888
Compare with similar skills
Debug 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 |
|---|---|---|---|---|---|---|
| Debug this skillmozilla/firefox-devtools-mcp | 468 | — | ~241 | Automated safety check: Pass | Custom licence | |
| MCP Server Builderanthropics/skills | 180k | 62 repos | ~2.3k | Automated safety check: Pass | Apache-2.0 | |
| MCP Server BuildershareAI-lab/learn-claude-code | 78k | 5 repos | ~1.2k | Automated safety check: Pass | MIT | |
| MCP Integration for Pluginsanthropics/claude-plugins-official | 37k | 11 repos | ~3.1k | Automated safety check: Pass | Apache-2.0 | |
| Figma use_figma Plugin API Ruleswarpdotdev/warp | 65k | 4 repos | ~4.4k | Automated safety check: Pass | AGPL-3.0 | |
| Stitch to Remotion Walkthrough Videosgoogle-labs-code/stitch-skills | 8.4k | 6 repos | ~3.2k | Automated safety check: Notes | Apache-2.0 |
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MCP Integration for Plugins
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Explains how to bundle Model Context Protocol servers in a Claude Code plugin, covering config files, stdio, SSE, HTTP and WebSocket server types, and authentication.
Figma use_figma Plugin API Rules
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MCP Development
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More from mozilla/firefox-devtools-mcp
Web Performance
mozilla/firefox-devtools-mcp
Find and fix why a website is slow by capturing and analyzing a Firefox performance profile, or by analyzing a profile the user already has (a saved file or a profiler.firefox.com share link).
Browser Automation
mozilla/firefox-devtools-mcp
This skill should be used when the user asks about browser automation, testing web pages, extracting content, filling forms, taking screenshots, or monitoring console/network activity.
Firefox Devtools Diagnose
mozilla/firefox-devtools-mcp
Diagnose Firefox DevTools MCP setup issues. An agent skill from mozilla/firefox-devtools-mcp.
Navigate
mozilla/firefox-devtools-mcp
Navigate Firefox to a URL and take a DOM snapshot for interaction
Screenshot
mozilla/firefox-devtools-mcp
Take a screenshot of a URL or the current page. An agent skill from mozilla/firefox-devtools-mcp.
Related
Works with
Questions about Debug
What does Debug do?
Show console errors and failed network requests. An agent skill from mozilla/firefox-devtools-mcp. Debug is an agent skill from mozilla/firefox-devtools-mcp.
How do I install Debug in Claude Code?
Run `npx skills add mozilla/firefox-devtools-mcp --skill debug -a claude-code`. Or copy the skill folder (plugins/firefox-devtools-mcp/skills/debug in mozilla/firefox-devtools-mcp) into .claude/skills/debug in your project. Claude Code loads it when a task matches its description.
How do I install Debug in Codex?
Run `npx skills add mozilla/firefox-devtools-mcp --skill debug -a codex`. Or copy the skill folder (plugins/firefox-devtools-mcp/skills/debug in mozilla/firefox-devtools-mcp) into .agents/skills/debug in your project. Codex loads it when a task matches its description.
Can I use Debug 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-devtools-mcp --skill debug -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/debug, .gemini/skills/debug, .github/skills/debug and .opencode/skills/debug in your project.
What does Debug need to run?
SKILL.md names no scripts, command-line tools or credentials: Debug is instructions for the agent only.
Does Debug access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Debug 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 Debug use?
Debug 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 Debug use?
About 241 tokens (SKILL.md is roughly 964 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 Debug?
Skills that share tags, products or a category with Debug: MCP Server Builder (anthropics/skills, 180k stars), MCP Server Builder (shareAI-lab/learn-claude-code, 78k stars), MCP Integration for Plugins (anthropics/claude-plugins-official, 37k stars) and Figma use_figma Plugin API Rules (warpdotdev/warp, 65k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Debug?
mozilla (a GitHub organization) maintains it in mozilla/firefox-devtools-mcp, which has 468 GitHub stars. The repository holds 6 skills in this directory. The repository was last updated on October 6, 2026.
Source: mozilla/firefox-devtools-mcp on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.