With that said, I often find myself leaning on the debug flow for non-errors e.g. UI/UX regressions that the models are still bad at visualizing.
As an example, I added a "SlopGoo" component to a side project, which uses an animated SVG to produce a "goo" like effect. Ended up going through 8 debug docs[0] until I was satisified.
Unless the agent doesn't know what it's doing... I've caught Gemini stuck in an edit-debug loop making the same 3-4 mistakes over and over again for like an hour, only to take the code over to Claude and get the correct result in 2-3 cycles (like 5-10 minutes)... I can't really blame Gemini for that too much though, what I have it working on isn't documented very well, which is why I wanted the help in the first place...
My guess is that the MCP was easy enough to add, and some tools only support MCP.
Personal opinion: MCP is just codified context pollution.
I'm biased because my company makes a durable execution library, but I'm super excited about the debug workflow we recently enabled when we launched both a skill and MCP server.
You can use the skill to tell your agent to build with durable execution (and it does a pretty great job the first time in most cases) and then you can use the MCP server to say things like "look at the failed workflows and find the bug". And since it has actual checkpoints from production runs, it can zero in on the bug a lot quicker.
We just dropped a blog post about it: https://www.dbos.dev/blog/mcp-agent-for-durable-workflows