Stateful servers like chrome-devtools don't work with mcp-cli

[filipeestacio]

Stateful servers like chrome-devtools don't work with mcp-cli

The Problem

I'm trying to use chrome-devtools-mcp to automate some browser testing, but each mcp-cli call command spawns a fresh server process. This means the browser state gets lost between commands - I can't navigate to a page, then fill out a form, then click a button. Each command starts from scratch.

What I'm trying to do

# Step 1: Open browser to staging site
mcp-cli call chrome-devtools new_page '{"url": "https://admin.staging.mysite.com"}'
# ✓ Works - browser opens

# Step 2: Fill in login email
mcp-cli call chrome-devtools fill '{"uid": "1_5", "value": "user@example.com"}'
# ✗ Fails - new browser instance, previous page is gone

The second command spawns a new server, which tries to launch a new browser, but the profile is locked from the first command. Even if I use --isolated, I lose all the state from step 1.

This is the error I get:

The browser is already running for /home/filipe/.cache/chrome-devtools-mcp/chrome-profile.
Use --isolated to run multiple browser instances.

Why this happens

mcp-cli treats every command as independent - it starts the server, runs the command, stops the server. This works great for filesystem operations or one-off API calls, but browser automation needs the server (and browser) to stay alive across multiple commands.

What would help

Add session management so I can keep a server running across multiple commands:

# Start a persistent session
mcp-cli session start chrome-devtools --name browser

# Now these all use the same browser instance
mcp-cli session call browser new_page '{"url": "https://admin.staging.mysite.com"}'
mcp-cli session call browser fill '{"uid": "1_5", "value": "user@example.com"}'
mcp-cli session call browser fill '{"uid": "1_8", "value": "password123"}'
mcp-cli session call browser click '{"uid": "1_12"}'
mcp-cli session call browser take_screenshot '{"filePath": "/tmp/logged-in.png"}'

# Stop when done
mcp-cli session stop browser

This would:

• Keep the server process running between commands
• Maintain browser state across operations
• Allow multiple named sessions for different servers
• Stay backwards compatible with existing one-off commands

Use case

I'm trying to investigate our admin portal on staging by navigating through the UI, filling forms, taking screenshots, and checking console errors. This requires 15-20 sequential commands all operating on the same browser session, which isn't possible with the current architecture.

Other servers affected

This would also help with:

• mcp-server-playwright (same browser automation issue)
• Database servers that maintain connections
• Any server with transaction or session semantics

Stateless servers like fast-filesystem and API query servers work fine as-is.

Environment

• mcp-cli: 0.3.0
• Server: chrome-devtools-mcp@latest
• Platform: Linux
• Config: Standard mcp_servers.json with npx launcher

Related

• only show STDERR with -v or -debug #17 - STDERR suppression request
• Environment variable warnings shown for all servers, not just the one being queried #20 - Environment variable warnings

Happy to test a PR if you decide to implement this, or do some follow up work myself and see if there is something that I can contribute.

Would also be fine with just clear documentation if session management is out of scope and I should use a different approach for this use case.