Laravel Boost unable to start server

[riza-khan]

For context, I'm using Neovim with the MCP extension. In addition, I have docker-compose setup for my Laravel development.

For some reason, I cannot start the Laravel Boost MCP server and the error isn't very descriptive.

From the MCP Plugin I get an error that the parsed JSON has an error.

And with the command php aritsan mcp:start laravel-boost I get:

{"jsonrpc":"2.0","error":{"code":-32700,"message":"Parse error: Invalid JSON was received by the server."}}

Anyone tried this and been through this?

[Sandalanka]

This is a JSON-RPC parse error, which usually means that the server (Laravel Boost MCP server in this case) is outputting something that is not valid JSON. Since MCP expects strict JSON-RPC 2.0 messages, any PHP error, warning, or stray output (like whitespace, logging, HTML, etc.) will break it.

Let’s debug systematically:

1. Check PHP Artisan Command

Make sure you typed the command correctly:

php artisan mcp:start laravel-boost

(you wrote php aritsan in your message, which might just be a typo, but double-check it’s not that in your real terminal).

2. Verify No PHP Errors/Warnings

Run:

php artisan mcp:start laravel-boost -vvv

The -vvv flag increases verbosity and should reveal if PHP is outputting warnings/notices before JSON.

Also check your Laravel log (storage/logs/laravel.log) right after running the command.

3. Disable/Redirect Extra Output

Sometimes Xdebug, deprecation warnings, or logging middleware can dump text into stdout. MCP requires only JSON on stdout. To confirm:

php artisan mcp:start laravel-boost 2>error.log

Then inspect error.log. If you see PHP notices, they’re polluting the JSON stream.

4. Confirm Environment (Docker)

Inside your Docker container, is php pointing to the correct binary? Try:

php -v
php artisan --version

Make sure the Laravel Boost MCP package is installed inside the same container where you’re running Artisan.

5. MCP Server Package

If you’re using laravel-boost/mcp
(guessing), confirm it’s installed:

composer show laravel-boost/mcp

If not, install:

composer require laravel-boost/mcp --dev

Likely Causes

PHP warnings/notices (most common).

Wrong PHP command/environment (outside of Docker).

Package not installed or autoload broken.

JSON is being corrupted by extra output.

👉 Can you run this for me inside your container and paste the output?

php artisan mcp:start laravel-boost -vvv 2>&1 | head -n 20

That will show the first 20 lines, which should reveal whether JSON is coming out or if PHP is dumping errors.

Would you like me to also show you how to wrap the command so it forces only JSON output (ignoring warnings)? That way, even if you have noisy PHP output, it won’t break the MCP handshake.