Skills

Build or write a Skill, check it, and download it as a folder that Claude, ChatGPT and other AI apps can use.

Want a hand?

Copy this prompt into Claude, ChatGPT or another AI assistant, and it walks you through it step by step.

I want to make a Skill in PromptMason for my AI apps. Walk me through choosing between “Static Skill” and “Dynamic Skill”, filling in the “Front matter” card, and using “Download Skill” to get the folder.

Copy adds a short note about PromptMason and this guide's steps, so the assistant has what it needs.

A Skill is a set of instructions that an AI app follows when a job matches it. Skills are an open format: Claude, ChatGPT, Cursor, GitHub Copilot, Gemini CLI and many other AI apps support them. A Skill is saved as a folder with one file in it, called SKILL.md. The top of that file says what the Skill is called and when to use it. The rest is the instructions.

PromptMason makes that folder for you. You fill in a few fields, write or build the instructions, and PromptMason checks the result and downloads it as a .zip file. You never type the technical part at the top of the file. A Skill you already have as a .zip file comes in the same way (Import a Skill).

Two ways to make a Skill

	Dynamic Skill	Static Skill
How it’s made	From blocks, on the Build screen	Written as text, on its own editor screen
Where you start	Build, with Build a set to Skill	Prompts, then New, then Skill
When a block changes	The Skill changes too	Nothing happens: it has no blocks

Choose a Dynamic Skill when the instructions are made of parts you already keep and reuse, such as your tone of voice or a standard format. Fix a block once and every Skill that uses it is fixed.

Choose a Static Skill when you want to write the instructions once, exactly as you like, or when an AI app wrote them for you.

Everything else works the same for both: the fields, the checks, the files, the download and using the Skill in Chat. In PromptMason’s lists, the Kind column says Static Skill or Dynamic Skill.

Make a Dynamic Skill

Click Build in the sidebar.
At the top, set Build a to Skill. A Front matter card appears above the blocks.
Type a title in the box at the top. This is the name you see in PromptMason’s lists. If you leave the box empty, the Skill is saved under the Name from the card, exactly as you typed it.
Fill in the card (see The front matter fields).
Drag blocks onto the canvas, as for any prompt (Build a prompt). Tick Heading on a block to put its name above its text as a heading.
Click Save as Dynamic Skill, or Apply to save and keep building. Save as Dynamic Skill takes you to the Prompts screen with your Skill selected.

The preview on the right shows the finished SKILL.md. Click File above it to see the file’s exact text, with the --- lines, and Preview to go back to the formatted view. The instructions start with the title as a heading, then each block in order. A block with Heading ticked gets its name as a heading above it. A block without it carries on from the text above. A block with no text adds nothing, not even its heading. Hidden notes are left out.

Make a Static Skill

Click Prompts in the sidebar, then New, then Skill.
Type a title in the Skill title box at the top. This is the name you see in PromptMason’s lists. If you leave the box empty, the Skill is saved under the Name from the card, exactly as you typed it.
Fill in the Front matter card.
Write the instructions in the large box below it. It is a plain text box: PromptMason saves exactly what you type, so headings, links and tags written in Markdown stay as you wrote them. The Tab key moves to the next control instead of indenting. The buttons above the box (Bold, Italic, Heading, Bulleted list, Numbered list, Quote, Code and Link) type the Markdown for you. See Format with the toolbar.
The pane on the right shows the finished SKILL.md as you write, and counts its characters and lines. Click File, above the instructions, to see the file’s exact text, with the --- lines, and Edit to go back to writing.
Click Save, or Apply to save and keep writing. Save takes you to the Prompts screen with your Skill selected.

If AI assist is set up, it works on the instructions only. The fields at the top are never sent to a model. See Improve text with AI assist.

A Skill with a problem in its fields still saves. A problem stops the download and the copy, and the card shows what to fix.

The front matter fields

The Front matter card holds what an AI app reads first. It is pinned above the blocks on Build and above the instructions on the editor screen. Name and Description are always shown. The rest are under More fields, which opens by itself when one of them has something in it.

Field	What it is for
Name	Required. The Skill’s name, which also names the folder.
Description	Required. What the Skill does and when to use it. AI apps read this to decide whether to use the Skill, so a vague description means it is not used. It can be up to 1,024 characters. The line under the box counts them.
License	Optional, under More fields. A short name for the terms you share the Skill under, such as MIT.
Compatibility	Optional, under More fields. What the Skill needs, such as “Needs a web browser”. Up to 500 characters.
Allowed tools	Optional, under More fields. The tools the Skill may use, separated by spaces. Some AI apps ignore it.
Metadata	Optional, under More fields. Extra pairs of a name and a value, such as author and Alex Morgan. Click Add for each pair and Remove to take one away. Up to 20 pairs.

The description is also the item’s own Description, so you don’t fill it in twice.

If an AI app saved the Skill and wrote a field the card doesn’t have, the card says, for example, 1 other field kept from the saved file, with a Remove button. The field is kept and written back when you download, until you remove it.

How the name is checked

A Skill’s name can use only lowercase letters, numbers and hyphens, up to 64 characters, with no hyphen at the start or end and no double hyphens. AI apps require this, so PromptMason checks it as you type and never changes what you typed.

With the name box empty, the card says A Skill needs a name. Suggested: ‘pdf-processing’. (made from your title) with a Use it button.
With a name that breaks the rules, such as PDF Processing, the card explains the rule and offers the fixed name. Click Use it to take it.
A variable can’t be the name: The name can’t use a variable.

Claude may refuse a Skill whose name contains the word “claude” or “anthropic”. PromptMason lists this as a note, not a stop.

The description limit

Enforce a character limit, under Properties, normally limits a whole prompt. On a Skill it limits the description. Use it if a tool you upload to accepts shorter descriptions. The line under Properties says Applies to the description of this Skill.

Use variables for shared values

Values you reuse, such as your company name or the author, can be variables written as {{author}}. They work in the description, the license, the compatibility, the allowed tools, each metadata value and the instructions. The card says so once, under the description: Every field here except the name can use {{variables}}, such as {{author}}. They can’t be used in the name.

Variables are filled in when you download or copy the Skill, not when you save it, so changing a variable changes every Skill that uses it. A variable that asks each time is asked for then, in the Fill in your values window. A variable with no value is kept as written, such as {{client}}, and listed as a note. Hidden notes written as {{! … }} are left out of the finished file.

The counters and notes

Under the preview of the finished SKILL.md, a line counts its characters and lines, for example SKILL.md: 396 characters · 12 lines. A Skill over 500 lines shows a note that shorter Skills are followed more reliably, and suggests moving detail into a file. It is advice, not a rule.

Add files to a Skill

A Skill can carry extra files, such as a reference page the instructions point to, or a script. Under Files, click Add file:

New file keeps a file inside this Skill. Type its File path, for example references/pricing.md, then its text, and click Done.
Link a document uses one of your Markdown documents from the same library as a file. Choose the document, then type its File path. The document stays where it is and can be used by several Skills. Its text is read when you download.

Each file shows its size, whether it is Kept in this Skill or a Linked document, and whether the instructions mention it: Linked from SKILL.md or Not linked from SKILL.md yet. An AI app finds a file by the path written in the instructions, so mention each one, for example in a Markdown link such as [prices](references/pricing.md).

A file’s path uses / between folders, can’t start with /, can’t contain .., and can’t be SKILL.md. It can be up to 200 characters and 5 folders deep. Files are text only. A Skill can have up to 50 files, each up to 1 MB, and 10 MB in all. They don’t count toward the Free plan’s 15 prompts.

If you delete a linked document, the Skill’s download stops until you fix it: ‘references/pricing.md’ points to a document that is no longer in your library. If you archive it, its text is still used and a note says so.

Each time you change a file’s text, PromptMason records a version. Restoring an earlier version of the Skill from History brings back the files as they were. See Version history.

Download Skill

Save the Skill first. The buttons are grayed out with Save your changes first. while there is anything unsaved.
Click Download Skill. You find it in the pane on the Prompts screen, under the preview on Build, beside Edit and File on a Static Skill’s editor screen, and in a Skill’s right-click menu.
If a variable asks each time, type its value in the Fill in your values window and click Download Skill.
Choose where to save the file.

You get <name>.zip, named after the Skill’s name. Inside is one folder with the same name, holding SKILL.md and your files at their paths:

quarterly-report-writer/
  SKILL.md
  references/pricing.md

SKILL.md is plain text. Hidden notes are gone and variables are filled in.

When the download stops

If something is wrong, PromptMason doesn’t write anything. A window titled This Skill can’t be downloaded yet lists what to fix, and Copy SKILL.md and the chat picker stop for the same reasons. The messages are:

Message	What to do
A Skill needs a name.	Fill in Name, or click Use it.
The name can use only lowercase letters, numbers and hyphens, up to 64 characters, with no hyphen at the start or end and no double hyphens.	Take the suggestion with Use it, or fix the name.
The name can’t use a variable.	Type a plain name.
A Skill needs a description: what it does and when to use it.	Fill in Description. A description made only of variables with no value counts as empty.
The description is … characters. Skills can use up to 1,024.	Shorten it. If you set Enforce a character limit, the message names your own limit.
Compatibility can be up to 500 characters.	Shorten it.
License is too long., Allowed tools is too long., A Skill can have up to 20 metadata entries.	Shorten the field, or take out a pair.
The instructions start with their own front matter, the block between two — lines. Move its values into the Front matter fields above.	Delete that block from the instructions and put its values into the card instead.
‘…’ can’t be used as a file path.	Fix the path. The message says why.
Files can be up to 1 MB each, 50 files and 10 MB in all.	Remove or shorten files.
‘…’ points to a document that is no longer in your library.	Restore the document from Recently deleted, or remove the file.

Notes before it downloads

A note doesn’t stop the download. A window titled Download with these notes? lists them, with Cancel and Download anyway.

Note	What it means
{{client}} has no value, so it was kept as written.	A variable has no value, so its `{{name}}` is in the file. Give the variable a value, or click Download anyway.
Claude may refuse a Skill whose name contains ‘claude’.	Rename it if you want to upload it to Claude.
Claude may refuse a description with a tag in it.	The description has something like `<name>` in it.
This Skill has no instructions yet.	The file will have only the fields.
SKILL.md is over 500 lines. …	Advice to move detail into a file.
A linked document is archived, or a block is removed or unavailable	The note says what was used instead.

Import a Skill

Import brings a Skill that is already a .zip file into PromptMason. Use it for a Skill you downloaded from PromptMason on another computer, one you exported from Claude or another AI app, or one someone sent you.

Click Prompts, then New, then Import a Skill….
Choose the .zip file. A file that ends in .skill works too.

The Skill is added to your list and opens on the right. Its name, description and other fields are filled in from the top of its SKILL.md, and its files are kept at their paths. SKILL.md can be at the top of the zip or inside one folder, and the files can sit in that folder too.

A Skill always comes in as a Static Skill, because a zip holds the finished text, not the blocks it was made from. It counts as one prompt on the Free plan, and its files don’t count. Importing the same file twice gives you two Skills.

The Skill is checked the same way as one saved from a connected AI app (see Save a Skill from a connected AI app). A name that breaks the rules is fixed and reported, and a missing description is refused.

When something was changed or left out, a window called Skill imported tells you. It can have up to three lists:

Changed to fit: what PromptMason fixed, for example a name made lowercase.
Not brought in: files that couldn’t come in. A Skill’s files are text only, so a picture or any other file that isn’t text is left out, and so is a file over 1 MB. Each is listed by name, for example ‘logo.png’ isn’t a text file. The rest of the Skill is saved.
Worth knowing: notes about the Skill, such as a name that uses a reserved word.

If the Skill can’t be imported, a window called This Skill can’t be imported says why, and nothing is added to your library:

This .zip has no SKILL.md in it, so it isn’t a Skill. The file must be called SKILL.md, in capital letters.
This .zip holds more than one Skill. Zip each Skill on its own and import them one at a time.
The zip is password protected, or damaged.
The SKILL.md has no description, or its fields can’t be read. The message says what to fix.

Copy SKILL.md

Copy SKILL.md puts the finished file on the clipboard as plain text, filled in and checked the same way as the download. Use it to paste a Skill into an AI app that takes text. The pane in the Chrome extension has the same button, but no download (The Chrome extension).

Save a Skill from a connected AI app

An AI app that is connected to PromptMason can save a Skill straight to your library. Ask it, for example: Save this Skill to PromptMason. It sends the whole SKILL.md, with the fields at the top, using the save_skill tool. See Connect an AI agent through MCP.

PromptMason reads the fields, saves the name and description into the card, and saves the instructions exactly as sent. It tells the AI app what it changed:

A name that breaks the rules is fixed and reported, for example The name ‘PDF Processing’ was changed to ‘pdf-processing’.
A list of allowed tools is joined with spaces.
A name that is missing is taken from the first heading of the instructions.

Only what can’t be fixed is refused, and the AI app is told why in plain words. A missing description is refused: A Skill needs a description: what it does and when to use it. So is a description over the limit, or front matter that can’t be read.

The saved Skill is a Static Skill. It has its own files if the AI app sent some. To change its text later, ask the AI app to update it (update_skill), which records a new version. A Skill built from blocks is changed with its blocks instead, and an AI app can read it with get_skill. See MCP tools.

Get a Skill as a zip file from a connected AI app

An AI app that is connected to PromptMason can also get a Skill as a zip file, the same file Download Skill saves, with the get_skill_zip tool. Ask it, for example: Get my quarterly report Skill from PromptMason as a zip file. It gets the file, its name and a checksum, so it can check that nothing changed on the way. A Skill you haven’t changed gives the same file every time. It works in Read-only mode too. See MCP tools.

Use a Skill in Chat

Every Skill you have is in the Skill picker in a chat’s header, under Your skills, marked Static Skill or Dynamic Skill. Choose one and the chat follows it from its next message on. You can also type / at the start of the message box and pick a Skill from the list: the box then starts with the Skill’s name, such as /meeting-notes-helper, and you type your message after it.

The chat is sent the finished SKILL.md, up to 20,000 characters. A chat can’t read a Skill’s files, and a Skill that has some says so under its name. A Skill with a problem shows This Skill can’t be used yet: and the first problem. See Run prompts in Chat.

Add a Skill to Claude or ChatGPT

Download the Skill first. Then:

In Claude (claude.ai):

Click your name at the bottom left, then Settings, then Capabilities, and make sure Code execution and file creation is on.
In the left sidebar click Customize, then Skills.
Click +, then + Create skill, then Upload a skill.
Choose the .zip file you downloaded.
Make sure the switch next to the Skill is on. Start a new chat and ask for something the description says it is for.

In ChatGPT:

Open Skills. It is in the sidebar, or under your name or picture. Where it sits can differ by plan.
Click Create, then Upload from your computer.
Choose the .zip file. ChatGPT checks it first and tells you if something is wrong.

Other AI apps that support Skills, such as Cursor, GitHub Copilot or Gemini CLI, take the same folder: unzip it where that app keeps its Skills. The app’s own help says where.

An AI app has its own rules, which can change. If one refuses a Skill, it names the reason. Fix that in PromptMason and download again.

Skills and the Markdown documents switch

A Skill isn’t a Markdown document. A document stays a plain document: no fields, no checks and no download. See Markdown documents. Settings → Features → Markdown documents hides the Document entry, never Skill.