ask agent to come up with categories (#4973)

https://www.notion.so/futuresearch/Classify-auto-generate-categories-if-user-doesnt-specify-MCP-tool-desc-fix-325e89b7a667819fb37fca157b124c2f

- suggest the agent to pick categories for classify if not provided
EXCEPT it is very unclear -> then ask the user

I can understand that in many situations it is nice if CC comes up with
categories but there are (also from my experience) many cases where this
is so ambiguous that CC should double check with the user (instead of
just going ahead with a wild guess), and I think this works really well
with this PR:

Sourced from commit b14de82f335f303cea7f7ac3a0382fc541ef5af6

Author: straeter

futuresearch-mcp/src/futuresearch_mcp/tools.py

@@ -758,6 +758,8 @@ async def futuresearch_classify(
 ) -> list[TextContent]:
     """Classify each row of a dataset into one of the provided categories.
 
+    If the user does not provide categories, try to come up with a few meaningful categories yourself. If this is hard and it is important that the user defines the categories, ask him to provide or describe them before you proceed.
+
     Uses web research that scales to the difficulty of the classification.
     Each row is assigned exactly one of the provided categories.