Agentailor

Skills

Agent skills for building AI agents.

Give your coding agent reusable guidance for designing tools, writing agent instructions, and building eval cases.

Each skill packages guidance from Agentailor articles into a SKILL.md file and supporting references. A compatible coding agent can load that guidance when the task matches. Choose the skill that fits your work, install it, then describe what you want to do.

Use with Claude Code or a coding agent that supports the Agent Skills specification. The source and references are open in the agentailor/skills repo.

Tool Design

tool-design

Design tools an AI agent can actually use — framework- and language-agnostic.

When to use it
You are adding tools or your agent picks the wrong tool, sends invalid inputs, or gets too much output.
What it helps you produce
Clearer tool definitions, focused outputs, and a checklist to review them.
What the skill covers

Five production-tested principles for tools an agent picks correctly, calls with valid inputs, and reads back without flooding its context — plus a validation checklist and worked examples. Applies whether the tool is an MCP server tool, a LangChain/LangGraph tool, or a plain function-calling definition, in TypeScript, Python, or otherwise.

Run in your project directory with Node.js and npx available. The installer lets you choose your coding agent.

install
npx skills add agentailor/skills --skill tool-design

After installing, try this

try tool-design
Use the tool-design skill to review my MCP tools for ambiguous names, invalid-input risks, and oversized responses. Propose concrete improvements.

source:repoWriting Effective Tools for AI Agents

Agent Prompt Engineering

agent-prompt-engineering

Design system prompts for autonomous, tool-using agents that run in a loop.

When to use it
You are writing agent instructions or your agent makes poor decisions about its next step.
What it helps you produce
Instructions with clearer decisions, boundaries, and stopping conditions.
What the skill covers

The principles, heuristics, and evaluation strategy that make an agent reliable when it decides its own steps — with worked prompt examples and the anti-patterns to avoid. Reach for it when writing agent instructions, a system prompt, or an agent config, or when an agent is making poor decisions.

Run in your project directory with Node.js and npx available. The installer lets you choose your coding agent.

install
npx skills add agentailor/skills --skill agent-prompt-engineering

After installing, try this

try agent-prompt-engineering
Use the agent-prompt-engineering skill to review this agent’s instructions for unclear decisions and stopping conditions. Suggest changes and explain how to evaluate them.

source:repoThe Art of Agent Prompting

Agent Eval Cases

agent-eval-cases

Decide which agent behaviors are worth an eval case, then write those cases.

When to use it
You have observed agent failures and need regression cases in your existing eval harness.
What it helps you produce
Focused cases with appropriate graders, based on failures you have actually seen.
What the skill covers

The workflow that turns observed failures into a small, honest eval suite: elicit real failures instead of inventing them, push each down to the cheapest layer that can catch it, group what survives by defect class, pair every case that pushes a behavior with one that bounds it, and pick graders by whether the target has one spelling or many. Also covers reading the first red run — why a case that passes before you fixed anything is a weak test. Harness-agnostic: it writes into whatever suite you already have.

Run in your project directory with Node.js and npx available. The installer lets you choose your coding agent.

install
npx skills add agentailor/skills --skill agent-eval-cases

After installing, try this

try agent-eval-cases
Use the agent-eval-cases skill to turn these observed failures into focused eval cases in my existing harness. Ask me for failure examples if I have not provided them.

source:repoHow to Write Your First AI Agent Evals

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Read this page as Markdown · All the ways to use Agentailor with AI