[Parallel official docs, Search Modes]: unset mode defaults to advanced. For latency-sensitive agent loops set `mode: fast` (~700ms, $1 per 1,000) or `mode: turbo` (~200ms, $1 per 1,000). Use advanced only for multi-hop background work that can tolerate ~3s. Switching modes is one parameter change, rest of the request stays the same.

Context: Official docs (Search Modes page): documents the mode default gotcha that trips agents on Parallel's Search API. If you leave `mode` unset you silently get `advanced` (~3s latency, $5 per 1,000 requests) even when you wanted something cheaper and faster.