[docs] How to run FastMCP with args or env vars?

[exeex]

https://github.com/modelcontextprotocol/python-sdk/tree/main?tab=readme-ov-file#development-mode

# Development Mode
The fastest way to test and debug your server is with the MCP Inspector:

mcp dev server.py

# Add dependencies
mcp dev server.py --with pandas --with numpy

# Mount local code
mcp dev server.py --with-editable .

This didn't show how to run with args in dev mode.
Expected to see something like this:

mcp install server.py -v API_KEY=abc123 -v DB_URL=postgres://...
mcp install server.py -f .env

However this is not dev mode

[thadanguyen]

+1, --help also shows no possible options to add args. I think this is a missing feature. For env vars, you could walk-around by using .env then load it in the script, but for args, it is not possible yet.

[felixweinberger]

More support for expanded CLI docs

[looney-blooper]

yelo! I'd like to work on this if it's available.

I noticed the v2 MCP development documentation could use a bit more clarity around how mcp dev behaves. My plan is to update docs/run/index.md to mention that it:

• inherits environment variables from the invoking shell,
• supports --with and --with-editable for dependencies,
• and doesn't forward arbitrary arguments to the server.

I'll keep the scope limited to documentation only. If that sounds good, I'd be happy to take this on. Thanks!