The minimum that's actually useful
Contact detail (email, WhatsApp or phone), what they're looking to get done, and one qualifying signal specific to your business (budget range, timeline, or business type) — that's usually enough to act on. Anything beyond that should earn its place, not be added by default.
Why more fields usually cost you the lead
Every additional required field is a point where a visitor can decide it's not worth finishing. See Why Contact Forms Don't Convert for the mechanics of this — the same logic applies to an AI intake's conversational flow, not just a static form.
Data you should NOT collect by default
Anything not needed to act on the inquiry — detailed company financials, unnecessary personal detail, or fields "just in case it's useful later." See AI Intake Security & GDPR for why data minimisation isn't just good UX, it's a real compliance consideration.
How this connects to CRM fields
What you collect at intake should match what your CRM actually uses to route and follow up — see What CRM Fields Should a Service Business Collect for the other half of this question.
Questions
Should I always collect a phone number?+
Only if your team actually calls leads — if follow-up is email/WhatsApp only, a phone field just adds friction.
What about company size or budget?+
Useful if it changes how you'd respond — skip it if every lead gets the same next step regardless.
Does this apply to the AI Sales Manager specifically?+
Yes — it's configured around exactly this minimal-necessary-fields principle, not a generic long-form questionnaire.