← Research highlights

Ongoing project · 2026

Benchmarking Coding Agents on Underspecified Tasks

Yiwei Yang · University of Washington

Knowing when to ask

Real requests to coding agents are often missing a key detail. A good agent should notice and ask, but only when the question is worth the user's time. This project builds a benchmark from real agent sessions to measure whether coding agents ask the right clarification questions, and how much it costs when they don't.

18%Runs where Fable 5.1 asked for clarification
60%Of its questions were low-value, vs. an 80% base rate
23%Final-state pass rate

Preliminary results on the current 171-task benchmark. Numbers may change as the work continues.

From real sessions to tasks

4,677Real coding-agent sessions mined
1,067Cases where the agent proceeded on an underspecified request instead of asking
171Tasks with reproducible repository states

How the benchmark works

  1. Find missed questions

    Identify sessions where the agent went ahead on an underspecified request and the user later had to correct it.

  2. Rebuild the task

    Restore the repository state for each case and pair it with a sandbox and an executable verifier.

  3. Simulate the user

    A simulated user returns the original user's correction only when the agent asks about the missing specification.

  4. Price each question

    Score each question by its cost of not asking: tokens spent on tool calls and line edits along the wrong implementation path, plus the cost of undoing it.

Early observations

Status

This project is ongoing, and a paper is in preparation. If you are interested in the benchmark or would like to collaborate, please get in touch.