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Inspect an agent repository and optional traces, interview the user, write reviewed Task Specs, build and audit Harbor tasks, and bootstrap reusable project World Knowledge Skills. Use for agent evals, benchmark design, Task generation, controlled Environments, synthetic data,

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langchain-skills
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$ npx -y skills add langchain-ai/langchain-skills --skill eval-engineering --agent claude-code

How it fires

How this skill gets triggered: by you, by Claude, or both.

  • Fires itselfAuto-invocation. Claude auto-loads it when your prompt matches the work.Auto-invocation is when the right skill fires by itself at the right moment, driven by a FLOW.md router and a hook, instead of you invoking it by name. It is the difference between a skill being installed and a skill actually getting used.Read the full definition →
  • You can call itInvoke it directly when you want it.
  • Slash command/eval-engineering

Context preview

The summary Claude sees to decide when to auto-load this skill.

Inspect an agent repository and optional traces, interview the user, write reviewed Task Specs, build and audit Harbor tasks, and bootstrap reusable project World Knowledge Skills. Use for agent evals, benchmark design, Task generation, controlled Environments, synthetic data,

SKILL.md

eval-engineering.SKILL.md
name: eval-engineering
description: Inspect an agent repository and optional traces, interview the user, write reviewed Task Specs, build and audit Harbor tasks, and bootstrap reusable project World Knowledge Skills. Use for agent evals, benchmark design, Task generation, controlled Environments, synthetic data, Verifiers, Harbor runs, calibration, or continuous benchmark maintenance.

Eval Engineering

Flow

  • Inspect all inputs first: the repository, Harness, optional traces, existing

Tasks and runs, existing World knowledge, and the human goal. Identify the source files and skill references that apply before proposing work.

  • Create or update the small project World Knowledge Skill from reusable facts

in those inputs. Use it to propose one grounded Task.

  • Draft the Task Spec and World Skill together. Show both to the user, keep exact

Task truth only in `Task.md`, and refine both until the user approves them.

  • Implement the approved Task, validate its Environment and Verifier, run the

real Harness, inspect the full evidence, and fix only non-agent failures.

  • Reconcile the World Skill with what the run proved, then repeat this flow for

the next Task.

Terms

  • **Task Spec:** `Task.md`, which describes the input, relevant agent

conditions, Environment, scoring, fairness, and open decisions for one Task.

  • **Task:** the runnable instruction, Environment, and Verifier.
  • **Harness:** the complete agent Harbor runs, including prompts, model loop,

tools, hooks, memory, sessions, and adapter.

  • **Environment:** the files, data, services, identity, permissions, network,

clock, and mutable state around the Harness.

  • **Verifier:** independent checks that score the result or mark a run invalid.
  • **World Knowledge Skill:** a repository-local skill with reusable

project-specific knowledge, references, scripts, assets, and tests that help generate Task Specs and build future Tasks.

  • **Spec2Task:** the full loop that turns a reviewed Task Spec into an audited

runnable Task. Follow [Task implementation](references/task-implementation.md) for its concrete build order and reference routing.

Reference routing

Read each reference when its decision appears:

| Need | Read | |---|---| | Inspect source, traces, the Harness, dependencies, access, and existing evals | [Discovery](references/discovery.md) | | Bootstrap or update reusable project knowledge | [World knowledge](references/world-knowledge.md) | | Propose Tasks and write the single Task Spec | [Task design](references/task-design.md) | | Build data, services, access, state, and reset | [Environment building](references/environment-building.md) | | Create structured or natural-language data | [Synthetic data](references/synthetic-data.md) | | Define independent evidence and scoring | [Verifier design](references/verifier-design.md) | | Apply Spec2Task to turn a reviewed Spec into an audited Task | [Task implementation](references/task-implementation.md) | | Compare model runs and classify failures | [Calibration](references/calibration.md) | | Package and run Harbor tasks | [Harbor](references/harbor.md) | | Adapt a known benchmark design | [Benchmark patterns](references/patterns.md) | | Build multi-turn conversations | [Multi-turn simulation](references/multi-turn-simulation/guide.md) | | See World knowledge learned across two Tasks | [Service-desk example](references/examples/service-desk.md) |

Reusable implementation resources:

  • Multi-turn [runner](references/multi-turn-simulation/runner.py), [model user](references/multi-turn-simulation/model_user.py), and [Harbor adapter example](references/multi-turn-simulation/harbor_example.py)
  • [Tool-schema comparison](scripts/compare_tool_schemas.py), which compares

supplied schema fragments but does not resolve external `$ref` targets

  • [Read-only SQLite state snapshot](scripts/snapshot_sqlite_state.py)

1. Inspect inputs and existing World knowledge

Review every input the user provides before proposing a Task. Use the guidance that matches each available input:

  • For a repository, Harness, traces, or dependencies, read

[Discovery](references/discovery.md).

  • For existing Tasks and runs, inspect their instructions, Environments,

Verifiers, rewards, trajectories, and final state. Read [Calibration](references/calibration.md) when run quality or failure causes affect the new design.

  • For an existing project World Skill, read

[World knowledge](references/world-knowledge.md), then check the sources and reusable methods that affect the new Task.

  • For human goals and constraints, read

[Task design](references/task-design.md).

  • For relevant benchmark examples, use the domain index and source callouts in

[Benchmark patterns](references/patterns.md).

Inspect the repository before asking questions that source and tests can answer. Follow the active Harness through prompts, models, tools, services, state, effects, and focused tests. Inspect existing Task instructions, parsers, Verifiers, reward paths, and run evidence.

If the user supplies traces, review complete runs or threads. Use traces to learn real requests, dependency behavior, state shapes, errors, and failure conditions. Do not treat a trace answer as independent truth.

If `.agents/skills/<project>-world/SKILL.md` exists, read it. Follow its routing only for knowledge relevant to the current Task. Check cited repository paths, commands, and scripts when their accuracy affects the design.

2. Propose and select a Task

Read [Task design](references/task-design.md) and use the index in [Benchmark patterns](references/patterns.md) to find the relevant domain and source callouts. Focus on that domain unless the Task crosses another one. In the first user-facing design response after inspection, propose one Task grounded in repository evidence, supplied traces, existing coverage, or a human priority. State:

  • the real work and capability;
  • the condition that makes the case
Read more
Ships withlangchain-skills

⚠️ — This project is in early development. APIs and skill content may change. Agent skills for building agents with LangChain, LangGraph, and Deep Agents. For LangSmith-specific trace and dataset workflows, use langsmith-skills.

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