Would it make sense to create a Rector MCP server?

[ruudk]

Sometimes I wonder if it would make sense to have a Rector MCP server, that is able to perform refactoring initiated by AI's.

Sure, an AI can try to create a rector.php file and then run it. But I imagine it takes a few times before it gets it right. If we would expose all the built-in Rector's as tools, it might make it easier.

I noticed that Rector is no longer allowing for class rename refactoring:

• [Renaming] Remove namespace renames in ClassRename, as it should only rename references, not move to new namespace rector-src#5487
• [Renaming] Remove rename class name rector-src#5488
• RenameClass not working #8596

But when we have an MCP server, it might make a lot of sense to let Rector handle this.

You could ask the AI to move a certain class to a new namespace. It would then refactor the whole codebase, by triggering a Rector rename MCP tool, that would find all the usages and update it. And even also update the related unit test, and move that too.

Did others think about this type of usage as well? Or is this a bad example for MCP?

[TomasVotruba]

I'd have to see this in action. My experience with GPT and Rector is poor, as there is not much learning material and AST is precision work.

How far are you from making a proof of concept to try out?

[ruudk]

I understand. But that's where MCP could help. Instead of the AI trying to guess things, it can delegate work to Rector. So how it works is we create a MCP server that exposes tools. These tools could be "move class" where it requires certain parameters like original location, and target location. Whenever the AI feels like it needs that tool, it will call the MCP server to do that. Basically sending a command with parameters to it. This will then do it. So whenever the "move class" is invoked, we configure Rector to do it, and let it cook. Once Rector is done, the tool call will be done, and return back to the AI.

So with MCP, the AI doesn't have to know anything about AST, or Rector internals. It only sees tools that the MCP server exposes.

This video explain the basics of it:
https://www.youtube.com/watch?v=_qH0ArjwBpE

There is also a PHP SDK for creating a MCP server: