Which LLM eval tool: best prompt and agent eval harness
Depot Pick: Braintrust. Runner-up: Langfuse (then LangSmith). Job: Prompt/agent eval harness. Updated 2026-10-28 (newest stored date on this page).
Regression-test agent quality in CI before ship.
Ready call for agents
MCP https://getagentdepot.com/api/mcp → decide {"task":"eval harness for my agent"}
HTTP GET /api/decide?jtbd=evalsNo key. The reply carries the pick, runner-up, the pick's sourced price with its date, and a recheck token.
Depot Pick: Braintrust
Editorial score 8.23 / 10 (curated estimate, as of 2026-10-28). Prices below are copied from the provider's own page; units are never converted.
capability eval workflows + dx.
| Item | Price (USD) | Source | Price as of | Last re-checked |
|---|---|---|---|---|
| Starter plan | $0 / month (plan base fee) | official page | 2026-10-21 | not reconfirmed |
| Pro plan | $249 / month (plan base fee) | official page | 2026-10-21 | not reconfirmed |
Runner-up 1: Langfuse
Editorial score 8.66 / 10 (curated estimate, as of 2026-10-28). Prices below are copied from the provider's own page; units are never converted.
| Item | Price (USD) | Source | Price as of | Last re-checked |
|---|---|---|---|---|
| Hobby plan | $0 / month (plan base fee) | official page | 2026-10-21 | not reconfirmed |
| Core plan | $29 / month (plan base fee) | official page | 2026-10-21 | not reconfirmed |
| Pro plan | $199 / month (plan base fee) | official page | 2026-10-21 | not reconfirmed |
| Pro + Teams add-on plan | $499 / month (plan base fee) | official page | 2026-10-21 | not reconfirmed |
Runner-up 2: LangSmith
Editorial score 8.09 / 10 (curated estimate, as of 2026-10-28). Prices below are copied from the provider's own page; units are never converted.
| Item | Price (USD) | Source | Price as of | Last re-checked |
|---|---|---|---|---|
| Developer plan | $0 / month (plan base fee) | official page | 2026-10-22 | not reconfirmed |
| Plus plan | $39 / month (plan base fee) | official page | 2026-10-22 | not reconfirmed |
Questions
- What does Agent Depot pick for Prompt/agent eval harness?
- Braintrust is the stored Depot Pick for the job evals. capability eval workflows + dx.
- What is the runner-up?
- Langfuse, then LangSmith. The ranking is editorial (scores as of 2026-10-28) and is not chosen by price.
- When should I not use Braintrust?
- Budget OSS-only — Langfuse/Phoenix. Already standardized on LangSmith datasets. Humanloop is sunset (Anthropic acquihire) — do not pick.
- How much does Braintrust cost?
- Starter plan: $0 per month (plan base fee), copied from https://www.braintrust.dev/pricing (price as of 2026-10-21). More rows are in the table on this page.
Picks are editorial and dated; community reports never change a pick or a score. Method: /methodology · Corrections: /corrections · Compare: Braintrust vs Langfuse