Dev Tools · 1h ago
Why AI Agents Need an Eval Harness: A $0.03 Lesson
A developer built an evaluation harness with 131 tests for an AI agent after a silent failure cost $0.03 per run and nearly lost a client. The failure stemmed from a semantic mismatch between the LLM's date interpretation and the database schema, which unit tests missed. The harness catches such cross-system errors by testing emergent behavior, semantic drift, and user intent coverage.
Meridian48 take
The story underscores a growing reality: traditional unit tests are insufficient for AI agents, and eval harnesses are becoming a necessary part of the development stack.
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131 Tests, 4 Layers: Why My AI Agents Get an Eval Harness First →
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