troubleshooting

troubleshooting is a skill for Claude Code, Codex from ChromeDevTools/chrome-devtools-mcp. It costs 40 tokens per session (1,548 once invoked), scanned B, original, Apache-2.0.

A troubleshooting guide for connection and target problems in the Chrome DevTools MCP server. Chrome DevTools MCP is a bridge that lets an AI assistant inspect and control a browser through developer tools.

In plain words
What is it for?
Use it to find the relevant MCP configuration, check flags and environment variables, and investigate common startup or browser-target errors.
Why use it?
It provides a fixed diagnostic order when browser pages cannot be listed, opened, or navigated, or when the server will not start. This avoids changing settings before checking the actual configuration and error type.

Skill for Claude CodeCodex

Part of the chrome-devtools-mcp plugin — 7 skills, 1 MCP server shipped together

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.

agentmods
npx agentmods add skills/chromedevtools/chrome-devtools-mcp/troubleshooting
Any agent
npx skills add ChromeDevTools/chrome-devtools-mcp --skill troubleshooting
Clone the repo
git clone --depth 1 https://github.com/ChromeDevTools/chrome-devtools-mcp

Made for: Claude Code, Codex.

Or install chrome-devtools-mcp, the plugin that ships this one along with the rest of its 7 skills, 1 MCP server.

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.

agentmods badge for troubleshooting

README.md
[![agentmods](https://agentmods.dev/badge/skills/chromedevtools/chrome-devtools-mcp/troubleshooting.svg)](https://agentmods.dev/skills/chromedevtools/chrome-devtools-mcp/troubleshooting)
Your own site
<a href="https://agentmods.dev/skills/chromedevtools/chrome-devtools-mcp/troubleshooting"><img src="https://agentmods.dev/badge/skills/chromedevtools/chrome-devtools-mcp/troubleshooting.svg" alt="Measured on agentmods" height="20"></a>
Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,548 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. Scan, not verified.
Origin original 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.

ModelPer sessionOnce invoked
Fable 5 $0.00040 $0.01548
Opus 5 $0.00020 $0.00774
Sonnet 5 $0.00008 $0.00310
Haiku 4.5 $0.00004 $0.00155

Measured 4d ago against content hash e534a7845f71, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

troubleshooting scanned grade B with 1 finding 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 4d 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.

Reads MCP configurationmediumAgent snooping

mcp.json carries server URLs and auth tokens; reading it lets a mod discover and abuse other integrations.

Your first action should be to locate and read the MCP configuration file. Search for the following files in the user's workspace: `.mcp.json`, `gemini-extension.json`, `.claude/settings.json`, `.vscode/launch.json`, or
Origin

Copies of this mod

8 near-identical copies found in the catalogue:

skills/troubleshooting/SKILL.md · 100 lines

How it starts

The opening of the file, as written. The whole thing — 100 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Troubleshooting Wizard

You are acting as a troubleshooting wizard to help the user configure and fix their Chrome DevTools MCP server setup. When this skill is triggered (e.g., because list_pages, new_page, or navigate_page failed, or the server wouldn't start), follow this step-by-step diagnostic process:

Step 1: Find and Read Configuration

Your first action should be to locate and read the MCP configuration file. Search for the following files in the user's workspace: .mcp.json, gemini-extension.json, .claude/settings.json, .vscode/launch.json, or .gemini/settings.json.

If you find a configuration file, read and interpret it to identify potential issues such as:

  • Incorrect arguments or flags.
  • Missing environment variables.
  • Usage of --autoConnect in incompatible environments.

If you cannot find any of these files, only then should you ask the user to provide their configuration file content.

Step 2: Triage Common Connection Errors

Before reading documentation or suggesting configuration changes, check if the error message matches one of the following common patterns.

Error: Could not find DevToolsActivePort

This error is highly specific to the --autoConnect feature. It means the MCP server cannot find the file created by a running, debuggable Chrome instance. This is not a generic connection failure.

Your primary goal is to guide the user to ensure Chrome is running and properly configured. Do not immediately suggest switching to --browserUrl. Follow this exact sequence:

  1. Ask the user to confirm that the correct Chrome version (e.g., "Chrome Canary" if the error mentions it) is currently running.
  2. If the user confirms it is running, instruct them to enable remote debugging. Be very specific about the URL and the action: "Please open a new tab in Chrome, navigate to chrome://inspect/#remote-debugging, and make sure the 'Enable remote debugging' checkbox is checked."
  3. Once the user confirms both steps, your only next action should be to call the list_pages tool. This is the simplest and safest way to verify if the connection is now successful. Do not retry the original, more complex command yet.
  4. If list_pages succeeds, the problem is resolved. If it still fails with the same error, then you can proceed to the more advanced steps like suggesting --browserUrl or checking for sandboxing issues.

Read the full file on GitHub · 100 lines

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.

  1. 4d ago First seen · 100 lines · 40 tokens per session scan B e534a7845f71

Subscribe to this mod's changes

troubleshooting is a skill published in the GitHub repository ChromeDevTools/chrome-devtools-mcp (50,411 stars, last pushed 2d ago), licensed Apache-2.0. It adds 40 tokens to every session and 1,548 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 1 finding (reads mcp configuration). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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