A single threshold forces every borderline turn into the same bucket as the clearly hopeless ones. Three actions solve that: answer, verify, hand off. Here is the decision table a routing layer should implement, with the actions written out.
| Confidence band | Action | What runs | Who sees the turn | Log fields to add |
|---|
| Above the high cut | Answer | Single pass with normal retrieval | Customer only | route=answer, cut_high, cited_spans |
| Between the cuts | Verify | Second retrieval, entailment check against the source span, or a self-consistency sample | Customer only if verification passes | route=verify, check_result, retries |
| Below the low cut | Hand off | Human queue with transcript, attempts, and extracted constraints attached | Human agent | route=handoff, reason, transcript_id |
The verify band is where most of the engineering value lives, because it is where borderline cases get a second chance before a customer sees them. The cheapest verification is a grounding check: confirm that the claim in the draft answer is entailed by a retrieved span, and abstain if nothing supports it, a technique that outperformed temperature scaling and "rate your confidence" prompting in the calibration work above USQRD. An ensemble disagreement check, where you sample the answer three to five times at moderate temperature and measure agreement, is a good second option USQRD. The support-operations lesson is the same: one team cut incorrect responses by 60 percent after switching from pure generative responses to a retrieval-first design that referenced real resolution patterns from past tickets Bland's write-up of AI agent challenges in support.
For the hand-off band, what travels with the ticket matters as much as the routing itself. A good hand-off carries customer identity signals, timestamps, the user's exact request, prior attempts, and extracted constraints, and a clean handoff that keeps the customer from repeating themselves is one of the quality signals that separates real resolution from quiet abandonment Thinklytics on measuring AI support deflection. Escalation quality is what makes the low band defensible.
Setting the numbers is arithmetic, not taste. Pick a target error rate for auto-answered turns, say 2 percent. From your binned accuracy, find the lowest confidence where the bin error is at or under that target, and set that as the high cut. Then pick a tolerance for the verify band's cost (retrievals are cheap, human minutes are not) and find the confidence below which verification rarely recovers a good answer. That is the low cut. Where the low cut sits is also where escalation cost starts to dominate, so weigh it explicitly.
Worked example. Suppose you log 10,000 turns a month. Your calibration says turns above 0.88 are correct about 96 percent of the time, turns between 0.62 and 0.88 are correct about 80 percent of the time, and turns below 0.62 are correct about 45 percent of the time. Your sample says 55 percent of turns land above 0.88, 30 percent in the middle band, and 15 percent below. Auto-answering the top band gives you 5,500 answers at roughly 4 percent error, or about 220 wrong answers. Verifying the middle band with a grounding check that catches, say, 60 percent of the unsupported claims leaves roughly 240 wrong answers from 3,000 turns, and the rest either pass cleanly or route to a human. Handing off the bottom band protects 1,500 customers who were otherwise a coin flip. Now you can price the rule: compare the cost of 3,000 grounding checks plus the human minutes saved from rerouting wrong answers against the cost of 220 customer-facing errors, taking your own per-error cost from your refund and churn data. For context, human-handled inquiries are commonly priced at $4.13 to $6.00 each against $0.50 to $0.70 for AI interactions, so the arithmetic hinges on your own numbers rather than the averages Supportbench's review of deflection expectations.
The rule should not be static across all traffic. Some requests need a human regardless of score: refunds beyond standard limits, disputed fees, account recovery when verification fails, and anything that could bind the company. Low-confidence intent is another hard route, including competing intents, missing required parameters, and fallback spirals where the agent keeps asking clarifying questions without progress. Encode those as hard routes above the confidence rule, and make the reason codes specific enough that you can count them later.