add mypy

[hb1915]

We should add a static type checker to ensure that typing is consistent across the project, this is particularly important for the relationship between SemanticModel.query() and the mcp query tool.

[hb1915]

I can see the case for making limit in mcp.py a required parameter, and then maybe we just remove the = None default

[hachej]

Hi @hb1915 ,
The code based has changed a lot this week :)
Is it possible to re-apply the type checker ?