Create Specification Agent Skill

Turns the planning context of the current session into a spec issue in the tracker.

Context cost
1.1k tokensestimated from the bundle, loaded when it triggers
Bundle
3 files · 4.4 kBtext throughout, nothing executable
Licence
MITthe author’s own terms
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Turns the planning context of the current session into a spec issue in the tracker.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

productivity

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md3.0 kB · preview
--- name: create-specification argument-hint: "optional: a spec title, or a roadmap issue ref" disable-model-invocation: true ---
8# Create Specification
9
10Write a specification from the decisions that this session already made. Do not invent new decisions. An implementer must be able to build from the spec without questions. The spec becomes an issue in the tracker. The issue body is the specification. The implementation slices become its sub-issues through the create-issues skill.
11
12If the docs/ folder or docs/TRACKER.md is missing, stop. Ask the user to invoke the set-up-for-agents skill.
13
14## Steps
15
161. **Make sure that the context is sufficient.** Read the spec template ([assets/templates/spec.md](assets/templates/spec.md)). Examine each section. Make sure that you can fill it from this session's context. For a roadmap area, the context also includes the notes of the area's closed sub-issues. If you must invent content for a section, the context is not sufficient. Then read [../grill-me/SKILL.md](../grill-me/SKILL.md) and interview the user until the gaps close. Then start this step again. This step is complete when you can fill each section from real decisions.
17
182. **Connect the spec to the repository.** Explore the code that the spec touches, if you did not do this before. Use the vocabulary from docs/GLOSSARY.md in the full spec. Obey the ADRs in the area. Identify the seams where tests will attach to the feature. Prefer seams that exist. Put a new seam at the outermost interface that can observe the behavior. Use as few seams as possible. One seam is best. Propose the seams to the user. This step is complete when the user agrees with the seams.
19
203. **Write the draft** from the template. Do not include file paths or code snippets. They become incorrect quickly. There are two permitted exceptions:
21 - Signatures, type shapes, and API contracts at the seams that the spec adds or changes. A signature is a decision. A written signature lets an implementer build without questions.
22 - A snippet from a prototype that records a decision more precisely than prose. Examples: a state machine, a schema. Keep only the part that shows the decision. Give the source of the snippet.
23
24 This step is complete when each section of the template has content.
25
264. **Review the draft with the user.** Show the draft to the user, section by section. Apply the user's corrections. This step is complete when the user approves the draft.
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md490 words
Files3
LicenceMIT
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈60
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
1,040
on trigger
The instruction body and 2 supporting files, read only when the skill fires.
0.55%
of a 200k window
Ten skills this size would take about 5% of the window before you open a file.
050k100k150k200k context window

1.1k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Small enough to keep loaded permanently without thinking about it.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

3 files, 4.4 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md3.0 kB
  • agents/openai.yaml0.2 kB
  • assets/templates/spec.md1.2 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 3 files you can review in full before installing. The MIT licence covers the templates and examples as well as the instructions.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Create Specification · 1.1k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/create-specification/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/create-specification" ] && { [ ! -e .claude/skills/create-specification ] || { mv .claude/skills/create-specification "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/create-specification" .claude/skills/ && echo "Installed .claude/skills/create-specification"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add builtbystef/create-specification

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/create-specification/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/create-specification/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/create-specification" ] && { [ ! -e ~/.claude/skills/create-specification ] || { mv ~/.claude/skills/create-specification "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/create-specification" ~/.claude/skills/ && echo "Installed ~/.claude/skills/create-specification" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/create-specification/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Versionnot versioned
Publishedno release date on file
PriceFree
Referencebuiltbystef/create-specification

Versions

Its author publishes no version number, so there is nothing here to pin to: what you install is the folder as it stands today. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

Pinning

Nothing to pin to: this skill carries no version number of its own. What you install is what the folder holds on the day you install it.

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