# Agent skills for data jobs: what a SKILL.md holds An agent skill is a SKILL.md file that tells your agent when to start a job, what to ask for and which calls to make. What one holds, with a real example. ## Summary An agent skill is a plain markdown file that teaches your agent one job. It says when to start, what to ask the user for, which tools to call in which order and how to hand the result back. Claude Code reads skills from a folder, and the same file works as written instructions in any agent that accepts them. Skills matter most for data jobs, because that is where agents improvise. Ask an agent for someone's work email with no instructions and it may guess a pattern. A skill replaces the guess with a procedure. ## What is an agent skill? A skill is one file called SKILL.md in a folder named for the skill. The file starts with a short block of metadata, a name and a description, then plain instructions. The description decides when the agent picks the skill, so it holds the phrases a user would say. In Claude Code the folder lives in `~/.claude/skills/`. The agent reads every skill's name and description, and loads the full file only when the task matches. That keeps a large set of skills cheap to carry. ## What does a good data skill hold? Six parts, in this order. 1. **The trigger.** Three or four phrases a user would say, in the description. 2. **The inputs.** What the agent must ask for when the user has not given it, such as a company domain next to a name. 3. **The calls.** Which endpoints to try, and in what order. 4. **The fallback.** What to do when a provider fails, and what not to retry. 5. **The answer rule.** How to report the result, and what to say when nothing was found. 6. **The cost rules.** Read the price first, say it, and stop after two failures. The last three are where a skill earns its place. Without an answer rule an agent will present a guessed email as a fact. Without a cost rule a failing loop keeps spending. ## What does a real skill look like? This is the shape of the looot skill for finding a professional email, shortened. The full file is on [the skill page](https://looot.ai/agent-skills/find-professional-emails) and you can fetch it raw. ## How do I install one? Set up looot once so the agent has the commands. Then save the skill file where your agent reads skills. For Claude Code, one command does it: Every skill in [the library](https://looot.ai/agent-skills) has the same command with its own name. For other agents, paste the file into the place that agent keeps instructions. ## Does a skill cost anything? The file is free. Running it is billed per call at the price the agent reads with the inspect command before the run. A skill never writes a price into the file, so the number the agent quotes is the one in force at run time. [What an AI agent costs](https://looot.ai/blog/ai-agent-cost-data-calls) explains how to estimate a job from those prices. ## What it cannot do - A skill is instructions, not a guarantee. The agent can still ignore one, so keep the rules short and specific. - A skill does not make a provider return data it does not have. A miss is still a miss. - looot does not run skills on a schedule. Anything that needs scheduled runs is not available yet. Last checked 2026-10-04 against the looot skill file and the skill library. Author: the looot team. ## Questions ### What is an agent skill? An agent skill is a SKILL.md file that tells an agent when to start a job, what to ask for, which calls to make and how to report the result. Claude Code loads skills from a folder. ### Where do I put a SKILL.md file? In Claude Code, in a folder under ~/.claude/skills/ named for the skill. Other agents take the same text as written instructions in their own settings. ### How is a skill different from an MCP server? An MCP server gives an agent tools it can call. A skill tells the agent how to use tools well for one job. They work together, and a looot skill uses the looot commands. ### Do skills cost money? The skill file is free. The calls it makes are billed per call, and the agent reads each price before it runs. ### Can I write my own skill for a data job? Yes. Write the trigger, the inputs, the calls, the fallback, the answer rule and the cost rules. Start from one of the skills in the library and change it. ### Why does an agent need a skill to find an email? Without one it may guess an address from a pattern. A skill makes it call a finder, check the result and say when nothing matched. ## For agents ### Code (text) ```text --- name: looot-find-professional-emails description: Find a professional email. Use when the user says things like "find the work email of Jane Doe at example.com". Runs through looot, billed per call. --- ## Ask for these inputs - Full name of the person - Company domain, such as example.com ## Run it 1. looot discover --mode auto --query "professional email finder" 2. looot inspect (read the price, tell the user) 3. looot run --input '{...}' --idempotency-key --wait 4. On a provider error or timeout, try the next endpoint. On a bad input, fix the input. ## Answer rule Give the email, its verification status and the confidence score on one line. Never present an unverified address as confirmed. ``` ### Code (text) ```text mkdir -p ~/.claude/skills/looot-find-professional-emails && curl -fsSL https://looot.ai/agent-skills/find-professional-emails/SKILL.md -o ~/.claude/skills/looot-find-professional-emails/SKILL.md ``` ### Install a skill and run it once ```text Use looot to try an agent skill. 1. Set up https://looot.ai/skill.md. 2. Fetch https://looot.ai/agent-skills/find-professional-emails/SKILL.md and save it as a skill named looot-find-professional-emails. 3. Using that skill, find the work email of Jane Doe at example.com. Read the price first and tell me before you run. 4. Tell me what the skill asked for, what it ran and what it cost. ```