Thinkerbell
Thinkerbell — turning vague requests into clear requirements

Open source · MIT · Free forever

The AI Requirements Toolkit

The checklists, prompts, patterns, templates and diagrams I reach for to turn vague requirements into clear, testable ones — now with Claude/Codex Skills that run the whole workflow for you. Free, open, and ready to drop into your work.

GitHub starsMIT License

★ New — Claude/Codex Skills

The toolkit that runs itself

Copying prompts and filling templates is good. Having Claude or Codex do the work is better. Drop these Skills into Claude or Codex and it runs the whole workflow for you — asking the right questions, applying the method, shaping the output with the bundled templates, and self-checking against the bundled checklists. Five skills, one for every stage of the requirements lifecycle, that hand off to each other from first request to final test.

  1. 1
    requirements-start
    A thin business request arrives — it frames the problem, maps stakeholders, and plans your discovery or validation workshop.
  2. 2
    requirements-writer
    Drafts testable, traceable requirements, INVEST user stories, Given/When/Then criteria and measurable NFRs — with battle-tested feature patterns.
  3. 3
    requirements-reviewer
    Audits existing requirements for ambiguity, risk, gaps and readiness, and classifies every finding by severity.
  4. 4
    requirements-test-cases
    Turns acceptance criteria into executable test cases and a traceability matrix, so nothing ships untested.
  5. 5
    requirements-diagrams
    Generates tailored Mermaid diagrams — context, use case, lifecycle, sequence, traceability — ready to drop into a spec.
Install in Claude Code
/plugin marketplace add clarityisrare/ai-requirements-toolkit
/plugin install requirements-toolkit@ai-requirements-toolkit

Adds this repo as a plugin marketplace, then installs all five skills. Update later with /plugin marketplace update ai-requirements-toolkit.

Install in Codex
/plugin marketplace add clarityisrare/ai-requirements-toolkit
/plugin install requirements-toolkit
/reload-plugins

In Codex, install the GitHub plugin first — it's what resolves the marketplace from GitHub — then run the commands above.

Browse the skills →Free · prefer one skill? Copy its folder by hand.

The one move it's built around

Most requirements aren't missing — they're vague, and everyone reads them differently. The whole toolkit pushes in one direction: making that vagueness impossible.

Before

“The system should let users upload documents quickly and securely.”

After

“The system shall allow authenticated customers to upload PDF files up to 20 MB, virus-scanned before they become available and visible only to the customer and reviewers in the owning department.”

What's inside

Five Claude/Codex Skills plus 40+ plain-Markdown and Mermaid files across seven folders — run a skill, or copy a file and adapt the wording. Your choice.

How to use it

  1. Browse by task. Writing criteria? Start in prompts. Reviewing someone else's work? Start in checklists.
  2. Copy, don't depend. Take what's useful into your own repo or wiki and adapt it to your domain and glossary.
  3. Keep a human in the loop. The AI prompts and checklists assume a person makes the final call — the tools accelerate the work, they don't own it.

If it saves you time, star it

A star is the signal that keeps this growing — it tells me which pieces are worth expanding, and it helps other people find the toolkit. It costs you a click and means a lot.