ClaudeDojo · Skills Deep Dive
Most people use Claude like a goldfish: every chat starts from zero, and they re-type the same instructions, rules, and context they typed last week. Skills are the fix. A skill is instructions you save once that Claude finds and follows on its own, every time the situation calls for it. This page is a deep dive on how skills work, then a full worked example: the resume skill.
A skill is a recipe card you write once and Claude follows forever. You don't have to remember to use it: the card itself says when it applies ("use this when Andrew pastes a job posting"), and Claude checks its recipe box automatically. Write the recipe once, and every future chat already knows it.
The Deep Dive
In Claude Code, a skill is nothing exotic: a folder in ~/.claude/skills/ containing one file, SKILL.md. That file has exactly two parts, and understanding them is the whole deep dive.
The top of the file (the "frontmatter") is how Claude decides when to fire the skill without being asked. The description is the most important line you'll write: it should name the exact phrases and situations that mean "run this recipe."
--- name: resume-jd-tailor description: Use when I say "tailor my resume" or provide a resume plus a job posting. ---
Vague description, skill never fires. Specific description with real trigger phrases, it fires every time. That's the craft.
Everything under the frontmatter is what Claude does once the skill fires: numbered steps, rules to read first, files to use, what the output must look like, what it must never do. Write it like you'd brief a very capable new assistant, because that's exactly what it is.
One skill per job. A skill that tries to do five things triggers badly on all five. When you find yourself typing the same instructions into Claude a third time, that's a skill telling you it wants to exist.
The Worked Example: Resume Building
Now apply it. Tailoring a resume by hand for every application is how good candidates burn out at application #12. Instead: template once, rules once, skill once, and every job description after that costs you one sentence. Steps 1–3 are setup; step 4 is the rest of your search.
This is your template and your evidence locker in one file: every job, project, metric, and win you've ever had, in your favorite resume's exact layout, longer than one page is fine. You never send this version anywhere. Don't write it from memory; let Claude interview you:
Rules are the difference between "AI wrote this" and "this is exactly how I present myself." Every non-negotiable goes in one file, RESUME_RULES.md. Steal these to start:
# RESUME_RULES.md — Claude follows these every time
1. Fits on ONE page. Every bullet fits on one line.
2. No starting verb repeats anywhere on the resume.
3. Summary is 2 lines max, it does the cover letter's job.
4. Commas instead of em dashes. No AI-sounding patterns.
5. Never invent or move experience between employers.
6. Real working links only, never placeholder "#".
7. My four flagship projects always appear: [yours here]
Time to use the anatomy from the deep dive: ~/.claude/skills/resume-jd-tailor/SKILL.md, a trigger up top and the recipe below. You don't even have to write the file yourself:
What Claude writes will look like this:
--- name: resume-jd-tailor description: Tailor my master resume to a job description. Use when I say "tailor my resume" or provide a resume plus a job posting. --- 1. Read RESUME_RULES.md first. Rules win. 2. Pull the JD's top 6–8 requirements in ITS words. 3. Map each one to my strongest real evidence. 4. Rewrite the summary as the cover letter (2 lines). 5. Reorder and reword bullets to mirror the JD. 6. Audit: verbs, one page, links. Then save as Resume_<Company>_<Role>.md with a gap report.
From now on, a new posting is a 90-second job:
The skill fires on its own. You get back a one-page resume in the JD's own vocabulary (that's what both recruiters and AI screeners match on), plus a gap report: which requirements you cover strongly and which are thin, so you walk into the interview knowing exactly where to prepare a forward-looking answer instead of getting surprised.
The audit never gets skipped. At application #1 you'd check every rule yourself. At application #20, exhausted at 11pm, you wouldn't. The skill runs the full checklist every single time, and ten applications tailored this way beat fifty generic ones.
And notice what you just built: a repeatable system that does a job you used to do manually. That's the same pattern as your capstone, so if you build this, you already know how to build that. Capstone ideas by role →