DevTools MCP Server

Create an MCP (Model Context Protocol) server that exposes your DevTools traffic data to AI assistants. This enables Codex CLI, ChatGPT, and Claude Code to query your network traffic directly.

Looking for local-only? See the Ollama guide for a fully local setup without external dependencies.

What you'll build:

You: "What external APIs is my app calling?"

AI: [Calling get_hosts tool...]
"Your application is connecting to 16 external APIs:
- api.stripe.com (3 requests, all 200s) - /v1/customers, /v1/charges
- api.openai.com (2 requests, 401 errors) - /v1/chat/completions
- api.segment.io (2 requests, all 200s) - /v1/track
..."

You: "Are we leaking any sensitive data?"

AI: [Calling check_sensitive_data tool...]
"Found 5 requests with sensitive data:
- api.github.com: X-Api-Key header exposed
- httpbin.org: Password in request body
- www.googleapis.com: Database credentials in payload
..."

Available Tools

Tool
Use Case
Default Capture

get_traffic

Full HTTP details for debugging

60s, 500 requests

get_traffic_summary

Quick overview of traffic patterns

60s, 1000 requests

get_hosts

Map all external API dependencies

60s, 1000 requests

get_errors

Debug 4xx/5xx failures

60s, 1000 requests

check_sensitive_data

Security audit for leaked secrets

60s, 500 requests

get_processes

Which process/container made requests

60s, 1000 requests

get_payloads

Inspect request/response bodies

60s, 500 requests

search_traffic

Filter by host, method, status

60s, 1000 requests

get_connections

Network/TLS connection details

60s, 2000 events

All tools support up to 5 minutes of capture with seconds=300.


Prerequisites

  • Linux host with Qtap installed and DevTools enabled

  • Python 3.10+


Create the MCP Server

Step 1: Install Dependencies

Step 2: Create the Server

Save this as devtools_mcp.py:

Make it executable:


Connect to AI Assistants

Option 1: Codex CLI

Codex CLI is OpenAI's terminal-based coding assistant that supports MCP servers natively.

Add the MCP server to your config:

Or edit ~/.codex/config.toml directly:

Using a virtual environment? Replace python3 with your venv Python path:

Use it:

Codex will call get_hosts and analyze the results.


Option 2: ChatGPT Developer Mode

ChatGPT can connect to MCP servers via Developer Mode connectors. Since ChatGPT requires HTTPS, you'll need to expose your local server.

1. Start the MCP server with HTTP transport:

2. Expose your local server via HTTPS tunnel:

3. In ChatGPT:

  • Go to Settings > Connectors > Advanced Settings

  • Enable Developer Mode

  • Add a new connector with your tunnel URL


Option 3: Claude Code

Claude Code supports MCP servers natively via the CLI.

Add the MCP server:

Using a virtual environment? Replace python3 with your venv Python path:

Verify it's connected:

Use it in Claude Code:

Claude Code will automatically use the appropriate tools to analyze your traffic.


Example Prompts

Once connected, try these prompts:

Quick Overview:

  • "What's happening with my network traffic?"

  • "Give me a summary of all HTTP requests"

  • "How many errors are there?"

API Discovery:

  • "What external APIs is my app calling?"

  • "Which services are we depending on?"

  • "Show me all the hosts we're connecting to"

Security Audit:

  • "Are we leaking any sensitive data?"

  • "Check for exposed API keys or passwords"

  • "What credentials are being transmitted?"

Error Debugging:

  • "What's failing? Show me all errors"

  • "Why are requests to stripe.com failing?"

  • "Debug the 401 errors"

Process Attribution:

  • "Which process is calling the OpenAI API?"

  • "What requests is the Python process making?"

  • "Show me traffic by container"

Payload Inspection:

  • "What data is being sent to external services?"

  • "Show me the request bodies"

  • "What's in the response from api.github.com?"

Filtered Search:

  • "Show me all POST requests"

  • "Find requests to anything with 'stripe' in the host"

  • "Show only 500 errors"


Example Output

get_hosts()

check_sensitive_data()


Troubleshooting

"Cannot connect to DevTools API"

Ensure Qtap is running with DevTools enabled:

Verify it's accessible:

"MCP server not found" in Codex

Check your config path:

Ensure the Python path is absolute and the script exists.

"No HTTP traffic captured"

  • Ensure traffic is being generated during the capture window

  • Try increasing the capture time: get_traffic(seconds=120)

  • Check that Qtap is capturing HTTP (not just connections)

ChatGPT can't reach the server

  • Verify cloudflared/ngrok is running and the URL is correct

  • Check that the MCP server is listening on the right port

  • Ensure no firewall is blocking the connection


Next Steps

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