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Stop Guessing: Building a Clarification Gate for Text-to-SQL Agents

Explore an engineering solution to prevent Text-to-SQL agents from making unapproved business assumptions by implementing a clarification gate and handling uncertainty states.

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Inewgen
28 Oct 2026Source: Dev.to2 min read (0 views)
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Stop Guessing: Building a Clarification Gate for Text-to-SQL Agents

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  • Text-to-SQL agents can return wrong answers even when the SQL syntax and execution succeed.
  • Allowing an LLM to quietly choose business meanings introduces unapproved business assumptions.
  • A clarification gate categorizes states into RESOLVED, AMBIGUOUS, and UNSUPPORTED.
  • Clarification questions should be constrained business choices rather than free-form interpretations.

An enterprise database can easily feature multiple conflicting measures for a single metric. For instance, if an organization tracks booked revenue, invoiced revenue, and recognized revenue, a conventional Text-to-SQL agent might retrieve columns, pick one arbitrarily, generate SQL, and return 12.8 million euros without organizational alignment.

This issue differs significantly from inventing a nonexistent table. The model might use entirely real data and produce a plausible number with the wrong underlying meaning. The engineering remedy is not simply telling the LLM to be careful, but placing a clarification gate between semantic resolution and SQL execution.

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Stock photo for illustration only, not from the actual event

A robust query planner treats uncertainty as a first-class state, returning one of three specific outcomes:

  • RESOLVED: Sufficient governed evidence to proceed safely.
  • AMBIGUOUS: Multiple materially different valid interpretations exist.
  • UNSUPPORTED: Insufficient evidence or unavailable data sources.

The clarification gate framework highlights a crucial enterprise limitation: syntactic correctness does not guarantee semantic accuracy. Relying solely on vector similarity scores often leads to silent failures. Enforcing strict policy-driven boundaries and explicit verification steps transforms brittle text-to-sql tools into dependable enterprise systems.

To resolve concepts properly before selecting columns, systems must evaluate a semantic candidate set rather than a single retrieved column. This process distinguishes vector relevance from governed authority, ensuring that the system relies on approved policies rather than arbitrary model guesses.

Source: Dev.to

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