Add config file support

[nbarraud]

Add Config File Support

Adds JSON configuration file support to MCP Inspector, aligning with other MCP tools like Claude Desktop.

Motivation and Context

MCP Inspector currently requires command-line arguments and environment variables for each run, creating friction for developers who:

• Test against the same server configurations repeatedly
• Work across multiple MCP tools with inconsistent configuration methods

This feature brings consistency with Claude Desktop and other MCP tools, creating a unified developer experience.

How Has This Been Tested?

Tested with:

• Valid and invalid configuration files
• Multiple server configurations in a single file
• Various command and environment variable combinations
• Error handling scenarios

Breaking Changes

None. This change is backward compatible. Users can continue using command-line arguments while gaining the option to use configuration files.

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

The implementation provides:

1. JSON configuration file parsing
2. New CLI flags: --config to specify a configuration file and --server to select a server from the config
3. Robust error handling
4. Updated documentation with examples
5. An example configuration file

[olaservo]

I really like this idea, do you think there is anything here that needs to be tweaked or tested more? (Noticed in was in Draft)

[nbarraud]

I really like this idea, do you think there is anything here that needs to be tweaked or tested more? (Noticed in was in Draft)

Yes I'm working on a better version and decided to leave this as a draft rather than submit 2 PRs. I will update this PR soon and then submit it.