After this, you'll have one installed Skill that auto-fires on natural language, passes its own eval, and is wired to a Scheduled Task that runs it on your chosen cadence.
Before you start
Complete Create a Cowork Project that runs a recurring workflow first; this lesson builds the Skill that fires inside that Project, and Scheduled Tasks pair with the Project pattern from Lesson 2.
The idea
A Skill is a packaged prompt that Claude calls by name when your message matches its description. You build a Skill once; it shows up in every future Cowork session ready to fire. The hard part is not the prompt body. The hard part is the description, because the description is what decides whether the Skill fires when it should and stays quiet when it shouldn't.
Here is the before and after: without a Skill, you paste the same 200-word prompt into Claude every Monday to draft your team update. With a Skill named team-update, you type "draft this week's team update" in any Cowork session and the Skill fires automatically with the right instructions, the right format, and the right tone. No paste. No re-explaining. The 15 back-and-forth messages and 12,000 tokens of an unskilled run become 2 messages and 6,000 tokens once the Skill exists.
Two paths to build the first Skill: built-in Skill Creator (interview-based, lives inside Cowork) or makemyskill.com (third-party, web-searchable, faster but external). Start with the built-in one. It interviews you, generates a SKILL.md draft with a trigger description plus instructions, then runs an eval against sample scenarios so you can see whether it fires correctly before install. The eval step is the one most people skip and the one that catches a Skill that almost works. To install: Settings > Customize > Skills > + > Upload. From that point the Skill auto-fires on any matching message in any Cowork session; /command is a manual escape hatch.
Now try it: pick the one prompt you paste into Claude most often this week (the one you re-explain). Run the built-in Skill Creator on that. Pass the eval. Install. Pair it with one Scheduled Task. By next week, that prompt fires itself.
Build a Skill for the prompt you re-explain most; let a Scheduled Task fire it forever.
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Try it (18 min)
Watch out for
Paste this into Claude:
Use the skill-creator to help me build a skill for [the recurring task you paste prompts for most: writing your weekly team update, drafting LinkedIn posts, summarizing client meetings, etc.].
When the Skill Creator interviews you, answer specifically. "I write weekly team updates that always start with the headline metric, use 3 sections max (wins, blockers, next-week priorities), end with a single owner-tagged action, and stay under 400 words" beats "I write team updates".
After the SKILL.md is generated, do NOT skip the eval step. Click "View the eval results" and watch how the Skill fires against the sample scenarios. If it fires when it should not, tighten the "Do NOT use for..." line in the description. If it does not fire when it should, broaden the trigger phrases.
After install, test the Skill in three ways:
1. Type a request that should fire it ("draft this week's team update"). Should fire.
2. Type a request that should NOT fire it ("draft a long-form essay on team culture"). Should stay quiet.
3. Type a request adjacent to the trigger ("write a 1-1 prep doc for my manager"). Should stay quiet unless that was intended.
Tell me which of the three matched expectations and which did not.What good looks like:
What a good response looks like:
Skill installed. Three-test results:
1. "draft this week's team update". Skill fired. Generated draft with headline metric (engagement up 12%), 3 sections (wins / blockers / next-week priorities), single owner-tagged action (Alex to unblock the auth review by Wed), 372 words. Matched expectation.
2. "draft a long-form essay on team culture". Skill stayed quiet, Claude wrote in default voice. Matched expectation. The "Do NOT use for: long-form essays, opinion pieces, culture documents" line in the description did its job.
3. "write a 1-1 prep doc for my manager". Skill stayed quiet. Matched expectation, though Claude's default response was generic and weak. Possible next move: build a second Skill for /one-on-one-prep specifically, with its own description and instructions.
Eval observations before install:
- Original description triggered on "summarize the week" which caught my journaling prompts too. Added "Do NOT use for: personal journaling, weekly reflections, individual reviews" line. Re-ran eval. Cleaner.
- Trigger phrases tested: 4 of 5 fired correctly. Fifth ("can you put together this week's standup notes") did not fire. Added "standup notes" to the trigger phrases line. Re-ran eval. All 5 fired.
Skill is live. Ready to wire to a Scheduled Task for Friday 4pm in my Team Updates Cowork Project.Go deeper (5 min)
Paste this into Claude:
(Set this up via the UI inside the Cowork Project where this Skill will fire.) 1. Open the Cowork Project most relevant to the Skill you built in the first exercise (or create one if needed: Skills can fire in any Project). 2. Click "Scheduled tasks" > "New". 3. Write the prompt: "Fire the [your-skill-name] Skill. Pull the relevant inputs from this Project folder. Save the output as a draft in the folder. Don't send or post anything." 4. Pick a frequency that matches the task: Friday 4pm for weekly team updates, Monday 8am for weekly newsletters, daily 6pm for end-of-day summaries. 5. Save. Then leave the Desktop app open so the scheduled fire happens. On the next firing, a draft lands in the folder.
What good looks like:
When this breaks
Claude can do it for you
Open Cowork and say: 'Use the skill-creator to help me build a skill for [the task you do weekly]. Walk me through the interview, run the eval, then show me the install steps in Settings.' Claude runs the Creator end to end.
You can now
Type a natural-language request into a fresh Cowork session that matches your Skill's trigger. The Skill fires on its own (you see it activate); the output follows the Skill's instructions; the eval results from setup matched your expectations across should-fire, should-stay-quiet, and adjacent-request tests.
Key takeaways
Build a Skill for the one prompt you re-explain the most. Run the eval. Install it. Pair it with a Scheduled Task in the right Cowork Project. By next week, that prompt fires itself, and you have one fewer thing to remember.