Aider is not agentic.
I personally found MCP a must for some scenarios
* Search GitHub for ideas how to use API, best practices and etc.
* Convert Figma design to code
* In slack-driver development companies you can even search Slack for ideas
Claude Code on the other hand, based on user's request, is capable of:
- researching the codebase to understand what needs to be done
- planning a TODO list for itself
- implementing the TODO list item by item
- running tests or typecheck etc. and iterating until checks pass
Basically if you give a sufficiently detailed plan as markdown to CC, it is capable of autonomously implementing the plan from start to finish, and that could even take something like 20 minutes.