refactor: simplify search tool prompt for better accuracy
Tested with 16 subagents researching ground truth and 10+ query
variations against Kimi+Exa MCP flow.
Key findings:
- Previous prompt forced current year (2026) for ALL queries, causing
wrong years for past events (Eras Tour 2024, Deadpool 2024)
- Colon-ending format showed no improvement in neural search
- Long examples cluttered prompt without benefit
Changes:
- Removed colon format requirement (no benefit proven)
- Changed from "always use current year" to "use actual year for past
events" - fixes major accuracy issue
- Reduced search guidance from ~450 chars to ~150 chars (67% smaller)
- Reduced answer guidance from ~550 chars to ~120 chars (78% smaller)
Test results (10 queries):
- Before: 6/10 correct years (forced 2026 on 2024 events)
- After: 10/10 correct years (Deadpool->2024, ErasTour->2024, etc)
