add a mechanism to disable tools from the config

[nirinchev]

Allows disabling of tools by category, operation type, or name. Example config:

env: {
  "MDB_MCP_DISABLED_TOOLS": "atlas, write, list-indexes"
}

or as command line args:

--disableTools atlas write list-indexes

Fixes #54

[nirinchev]

@fmenezes @blva I've tried to map the atlas tools to operation types, but feel free to suggest more appropriate ones (or we can introduce new types if that'd make sense).

[gagik]

if this supports an array anyways we could just always do the split without the indexOf check

[fmenezes]

have we seen this pattern before? are there other MCP servers that allow disabling tools?

[nirinchev]

Yes, there's a handful of database-focused servers I've seen implement some form of protection against destructive operations. E.g. mcp-server-mysql has env variables such as ALLOW_INSERT_OPERATION, ALLOW_DELETE_OPERATION, etc. to control what tools are allowed. Alternatively, mongodb-lens has a 2-step confirmation, where it responds with a code and then verifies that the user has input it to go through with the operation. supabase-mcp-server similarly implements a 3-tier safety system.

I think this is ultimately important to instil confidence in users, especially with some agents being fairly opaque with what they're doing. I know most allow you to disable tools one-by-one, but with server updates, you run the risk of letting a destructive tool sneak in and wreak havoc on your data.

[fmenezes]

@nirinchev I was thinking here, what if all tools declared a list of tags instead of one category? this way we could have something like disableTools write and keep everything readonly but also we could disable atlas,destroy, allowing you to do writes without destroys but no access to atlas.

[nirinchev]

Right now we're kind of there, but with the caveat that all tools have exactly 2 "tags" - the category and the operation type. Therefore if a user specifies atlas, write, delete, they're disabling all tools in the atlas category, as well as all tools that have operation type write or delete. We can definitely make it even more flexible/generic by allowing arbitrary number of tags, but I wonder if that wouldn't overcomplicate things.

[fmenezes]

Rigth now we're kind of there, but with the caveat that all tools have exactly 2 "tags" - the category and the operation type. Therefore if a user specifies atlas, write, delete, they're disabling all tools in the atlas category, as well as all tools that have operation type write or delete. We can definitely make it even more flexible/generic by allowing arbitrary number of tags, but I wonder if that wouldn't overcomplicate things.

That works for me, just make sure to have a category for the main tools, could be 'tools', 'driver' or 'server'. At least we would be consistent.

[nirinchev]

What would be in the tools category? Right now I've used the same category names as the folder structure (that is atlas and mongodb) - happy to find better names, though driver is probably not what I'd go with.

[gagik]

Maybe clusters-read / clusters-write + database-read database-write? We can also have read/write which combines the two.

[fmenezes]

it works for me, just make sure to leave documentation on README.md otherwise it will be difficult for people to find out how to use these values