langsmith-evaluator

Creates LangSmith evaluation pipelines automating grading of agent and LLM outputs.

Updated Apr 12, 2026
One-click install
npx skills add https://github.com/dotlab-hq/torque --skill langsmith-evaluator-dotlab-hq
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: langsmith-evaluator
Source: https://github.com/dotlab-hq/torque/tree/main/.agents/skills/langsmith-evaluator
Command: npx skills add https://github.com/dotlab-hq/torque --skill langsmith-evaluator-dotlab-hq

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill provides a practical blueprint for building repeatable evaluation pipelines that standardize and automate grading of agent and LLM outputs within LangSmith projects and datasets.

Core Features & Use Cases

  • Evaluator Patterns: Guidance for both LLM-as-judge evaluators and deterministic custom code evaluators for objective checks.
  • Run Function Design: Instructions to capture outputs and execution trajectories, handle RunTree vs dict run objects, and align run outputs to dataset schema.
  • Deployment & Workflow: How to run evaluations locally with evaluate(), upload code evaluators via the langsmith CLI, attach evaluators to datasets or projects, and handle sandbox constraints.
  • Use Case: Validate a conversational agent's final answers and tool-call trajectories against an offline dataset or perform live quality checks on production runs.

Quick Start

Run a local evaluation by calling evaluate with your run function and a dataset named My Dataset to test evaluators before uploading.

Frequently Asked Questions about langsmith-evaluator

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I build a LangSmith evaluation pipeline for agent trajectories?

To build a LangSmith evaluation pipeline, design a run function that captures outputs and execution trajectories, ensuring you handle RunTree versus dict run objects and align run outputs to your dataset schema for automated grading.

How do I test LangSmith evaluators locally before uploading?

You test LangSmith evaluators locally by calling the evaluate() function with your run function and a target dataset, allowing you to validate evaluator logic before uploading code evaluators via the langsmith CLI.

Can I use LangSmith evaluators for live quality checks on production agent runs?

Yes, you can apply LangSmith evaluators to perform online project-level quality checks for agents implemented in Python or TypeScript, standardizing the grading of both final answers and tool-call trajectories.

Do I need LangSmith API authentication to run evaluation pipelines?

LangSmith evaluation pipelines require LangSmith API authentication to function, which is necessary for both offline dataset-based evaluations and uploading custom code evaluators to the sandbox environment.

What is the difference between LLM-as-judge and custom code evaluators in LangSmith?

LLM-as-judge evaluators grade subjective agent outputs using language models, while deterministic custom code evaluators perform objective checks, with both patterns requiring single-metric evaluator returns to function correctly.

Why does my uploaded LangSmith evaluator fail in the sandbox?

Uploaded LangSmith evaluators fail when they violate sandbox constraints or return multiple metrics instead of enforcing a single-metric evaluator return, requiring alignment with the uploaded evaluator sandbox environment.