You have explained the same job to a chat window again. The tone rules. The output shape. The facts it must never invent. Gemini Skills exist to end that loop, and the part most coverage buries is the file underneath them. Google built Skills on the open SKILL.md standard, so a skill you write once as a file you keep can go into Gemini and can also go into other assistants that read that same standard.
Google announced Skills on September 30, 2026, as reusable instructions that will replace Gems. The Gemini app rollout began on October 13, 2026. This tutorial follows the Gemini Apps Help pages and the Agent Skills specification, checked on November 11, 2026. It claims no test run of its own. The Verification section tells you how to judge the result in your own account.
What You Will Build or Learn
You will end with one working skill that drafts a product description from facts you supply. The example is small on purpose. Once the file works in Gemini, you will reuse that exact file outside Gemini, and you will learn where reuse stops. Scripts, files and tool access do not travel as reliably as the instructions do.
The gain is ownership. A skill built only inside one app lives at the mercy of that app. A skill kept as a file in your own folder can be edited, shared, stored with a project and loaded again when you change tools. Our profile of Microsoft APM, the package manager for agent skills, covers how teams share such files at scale. This tutorial covers the single skill version that anyone can do today.
The description at the top of a SKILL.md file decides when an assistant reaches for it. Illustration: Dirty Static
Before You Begin
Pick one job that repeats and has a checkable output. Product copy, meeting notes in a fixed shape, or a report in a house format all work well. A vague job makes a vague skill, and a vague description makes Gemini miss the moments when the skill should apply.
Two limits shape the whole method, and Google states both in plain terms. First, Skills in the Gemini app and Skills in Workspace apps do not sync. A skill you need in both places must be created in each place. Second, scripts inside an uploaded skill that need access to external websites are not supported in Gemini. A skill whose core is a web call may work in a coding agent and fail in Gemini, even though the instructions load in both.
Step 1: Write the Master SKILL.md File
Action: create a folder with a name in lowercase letters joined by hyphens, then create a file named SKILL.md inside that folder. The Agent Skills specification says the folder name must match the name field in the file, the name may use lowercase letters, numbers and hyphens only, and it may not start or end with a hyphen. The description may run to 1,024 characters at most, and it should say what the skill does and when to use it.
Save this example as the SKILL.md file inside a folder named draft-product-description:
---
name: draft-product-description
description: Drafts product copy from supplied facts for an online shop. Use when preparing a new product page or rewriting catalogue copy from a list of facts, price and materials.
---
# Draft a product description
Use only the facts the user supplies in the chat. Never invent a price, a material, a size or a delivery claim.
## Steps
1. Read the supplied facts and list any fact that is missing for a complete description.
2. If the price or the material is missing, ask for it and stop.
3. Draft a title of eight words or fewer from the product name and its main use.
4. Write two short paragraphs. The first states what the product is and who it suits. The second states the materials, the size and the care facts, when supplied.
5. End with one plain line that gives the price exactly as supplied.
## Output shape
Return the title on its own line, then the two paragraphs, then the price line. Keep the tone plain and factual.
Expected result: you hold one folder with one file, and the file has two parts. The frontmatter between the three dash lines carries the name and the description. The Markdown body below it carries the instructions, the steps and the output shape. Keep the body under 500 lines, as the specification advises, and move long reference material into separate files only when the skill truly needs them.
Step 2: Upload the File to Gemini
Action: open the Gemini web app, go to the Skills page, and at the top select Create and then Upload, as the Gemini Apps Help page describes. Select the SKILL.md file itself, or select the folder or a zip file that holds SKILL.md in its main folder. Select Open, add any extra files the flow offers, then select Upload. Review the skill, edit the name, description or instructions if the review screen shows a change you did not expect, then select Create at the top.
Expected result: the new skill appears on your Skills page with the name draft-product-description. Google lists a total limit of 100 MB for all files uploaded with a skill, and only plain text based files are supported for the upload route. If the upload fails, check for hidden files in the folder, such as a .DS_Store file, and remove them before you try again.
You can also build a skill inside Gemini with Create manually, with a template, or by asking Gemini in a chat to turn a good conversation into a skill. Those routes are faster for a one off skill. The file route in this step is the one that leaves you with a master copy you can reuse elsewhere, which is the point of this tutorial.
Step 3: Use the Skill in a Chat
Action: open a new chat and type a slash, or the at sign if your account shows the updated shortcut, then select draft-product-description. Paste a short list of real facts for one product, with its name, material, size and price, and ask for the description.
/draft-product-description
Facts: enamel mug, 350 ml, steel with enamel coat, white, price 18 dollars. For campers and desk use. Hand wash only.
Expected result: Gemini follows the output shape from the file. You get a short title, two paragraphs and a price line, and no claim that was absent from your facts. Leave one fact out on a second try, such as the price. The skill should ask for the missing fact and stop, as its instructions direct. That refusal is part of the design, not a failure.
Skills can also apply on their own. Google says Gemini can use an activated skill when the context of a task fits it, and you can turn a skill off on the Skills page if you want manual control only. You can also use more than one skill in a single task. Stack this copy skill with a second skill that holds your brand voice, and the chat will follow both sets of instructions in one answer.
Step 4: Reuse the Same File in Other Tools
Action: keep the draft-product-description folder as the master, and load that same SKILL.md into each other assistant you use that supports the Agent Skills standard. Google states the reuse promise in one line in its Workspace post: Skills are built on the open SKILL.md standard, and that allows you to copy skills you created on other platforms into the Gemini app and Workspace apps. The specification at agentskills.io defines the same file shape for every client that adopts it.
One master file, many rooms: each tool gets its own copy, so the folder you keep is the source that matters. Illustration: Dirty Static
Expected result: the instructions travel. The name, the description and the body should read the same in Claude, ChatGPT, a coding agent or Gemini CLI style tools that read the standard, subject to each tool and its own import route and folder rules. Follow the import steps that the tool itself documents, place the folder where that tool reads skills, and run the same product facts from Step 3 as your test input.
What does not travel deserves equal weight. Tools do not sync, so a fix you make inside Gemini never reaches the copy in another tool, and a fix in the master folder reaches no tool until you load the file again. File support, script support and tool access also vary by client. The Gemini help page limits uploaded skills to supported plain text files and blocks scripts that need external websites. Expect the words to carry over. Test the extras in each tool before you rely on them. Our guide to PlugVet checks for agent skills and plugins is a useful read before you load a skill written by someone else.
Step 5: Update the Master, Then Load It Again
Action: when the output drifts, change the master SKILL.md file first. Clarify the step that failed, add the missing edge case to the instructions, and save the file. Then update each place where the skill lives. In Gemini, Google notes that updating files in a skill means uploading the entire skill with its files again. You can also ask Gemini to update a skill inside the app, but keep that change in step with the master file or the copies will part ways.
Expected result: every copy traces back to one edited file, and your notes can name the date of the last update. If you skip the master and edit only inside one app, you now own two skills that share a name and differ in behaviour, which is the exact drift this tutorial set out to kill.
Verification
Start a fresh chat in Gemini, call the skill with a slash, and use facts for a product the skill has never seen. Check three things in the answer. The title and paragraphs follow the output shape. Every claim in the copy appears in the facts you supplied. The price line matches your supplied price exactly, with no added claim about delivery or stock.
Then run the same facts in one other tool where you loaded the file. The wording may differ, since a different model writes the copy. The shape, the missing fact behaviour and the ban on invented claims should hold in both places. If they hold in both, the file works as a portable skill, not just as a Gemini setting.
Finish with the Gems check. If you still hold Gems you care about, open the Skills transition notes in Gemini Apps Help. Google says Gems move to the Settings panel on November 17, 2026, and any Gems left in the app when support ends will move to draft Skills on their own. A manual pass now lets you turn your best Gems into clean SKILL.md files while you can still compare the old and new forms side by side.
Troubleshooting
| Problem | Likely cause | Fix |
|---|---|---|
| No Skills page appears in your account | The rollout is gradual, or the account type is not covered yet | Confirm you use a personal Google Account and that you are 18 or over, then check the web app, the mobile app and the Mac app. Wait for the rollout if none show Skills yet |
| The upload is rejected | SKILL.md is not in the root of the folder, the name breaks the naming rule, or the total file size passes 100 MB | Place SKILL.md in the main folder, make the skill name lowercase with hyphens and a match to the folder name, remove hidden files, and cut large reference files |
| Gemini never applies the skill on its own | The description is too vague for Gemini to match the task, or the skill is turned off | Rewrite the description to name what the skill does, when to use it and the words a request will use. On the Skills page, activate the skill if you want automatic use |
| The skill invents a price or a material | The instructions do not forbid added facts, or the test input left gaps with no rule for gaps | Add a plain rule that names the banned behaviour, plus a step that asks for a missing price or material and stops. Test again with one fact removed |
| The skill works in Gemini but is absent in Workspace | Skills do not sync between the Gemini app and Workspace apps | Create the skill again in Workspace from the same master file. Keep both copies tied to that one file for later updates |
| A script in the skill fails in Gemini | The script needs access to an external website, which Gemini does not support for uploaded skills | Keep the instructions portable and keep the script as an optional part for tools that support it. State that limit in the skill body so no reader expects the script to run everywhere |
| The same skill gives a different shape in a second tool | That copy is old, or that tool reads only part of the package | Load the current master file again in that tool, then rerun the Step 3 test input and compare the shape, not the exact wording |
Next Steps
Build a second small skill that does one narrow job well, such as a brand voice check, and stack it with the product copy skill in one chat. Two narrow skills that combine beat one giant skill that tries to govern every task, and each one stays easy to test on its own.
Save the master folders with the project they serve, in a repo or a shared drive folder your team can read. When a skill proves itself across two tools, that folder becomes part of the project record, in the same way a style guide does. Start with one skill, prove it in two places, and only then build the library.
Facts checked against Gemini Apps Help on creating and managing skills, the Google Workspace Updates post of September 30, 2026, with its November 9, 2026 update, and the Agent Skills specification at agentskills.io, on November 11, 2026. This procedure was verified against those documents and was not presented as a personal test run.
Sources
- Google, Gemini Apps Help: Create and manage skills for Gemini Apps
- Google, Gemini Apps Help: Write effective skills for Gemini Apps
- Google Workspace Updates, September 30, 2026: Introducing skills in the Gemini app and Workspace, plus what is next for Gems
- Agent Skills specification, agentskills.io
- Illustrations: Dirty Static
END OF TRANSMISSION
Stay curious. Question everything.
