Decomposes a specification or large requirement into a structured plan document and a list of small, verifiable, ordered tasks with acceptance criteria. It maps dependencies and slices work vertically to ensure each task is implementable in a single session.
Say it in your own words; the assistant finds this recipe by itself. Examples:
Use this skill when you have a clear specification or set of requirements that need to be converted into actionable development steps. It is ideal when a project feels too large or vague to start, when you need to estimate the scope of work, or when you need to parallelize work across multiple agents or team members. It is also useful for communicating scope and progress to human stakeholders.
Decompose work into small, verifiable tasks with explicit acceptance criteria. Good task breakdown is the difference between an agent that completes work reliably and one that produces a tangled mess. Every task should be small enough to implement, test, and verify in a single focused session.
When NOT to use: Single-file changes with obvious scope, or when the spec already contains well-defined tasks.
Before writing any code, operate in read-only mode:
Do NOT write code during planning. The output is a plan document saved to tasks/plan.md and a task list recorded in the task list target (see Output Files; default tasks/todo.md), not implementation.
Map what depends on what:
Database schema
│
├── API models/types
│ │
│ ├── API endpoints
│ │ │
│ │ └── Frontend API client
│ │ │
│ │ └── UI components
│ │
│ └── Validation logic
│
└── Seed data / migrations
Implementation order follows the dependency graph bottom-up: build foundations first.
Instead of building all the database, then all the API, then all the UI — build one complete feature path at a time:
Bad (horizontal slicing):
Task 1: Build entire database schema
Task 2: Build all API endpoints
Task 3: Build all UI components
Task 4: Connect everything
Good (vertical slicing):
Task 1: User can create an account (schema + API + UI for registration)
Task 2: User can log in (auth schema + API + UI for login)
Task 3: User can create a task (task schema + API + UI for creation)
Task 4: User can view task list (query + API + UI for list view)
Each vertical slice delivers working, testable functionality.
Each task follows this structure, whether it lands in the markdown task list or as an item in an external tracker (see Output Files):
## Task [N]: [Short descriptive title]
**Description:** One paragraph explaining what this task accomplishes.
**Acceptance criteria:**
- [ ] [Specific, testable condition]
- [ ] [Specific, testable condition]
**Verification:**
- [ ] Tests pass: [the repository's focused-test command]
- [ ] Build succeeds: [the repository's build command]
- [ ] Manual check: [description of what to verify]
**Dependencies:** [Task numbers this depends on, or "None"]
**Files likely touched:**
- `src/path/to/file.ts`
- `tests/path/to/test.ts`
**Estimated scope:** [Small: 1-2 files | Medium: 3-5 files | Large: 5+ files]
Arrange tasks so that:
Add explicit checkpoints to the task list target:
## Checkpoint: After Tasks 1-3
- [ ] All tests pass
- [ ] Application builds without errors
- [ ] Core user flow works end-to-end
- [ ] Review with human before proceeding
| Size | Files | Scope | Example |
|---|---|---|---|
| XS | 1 | Single function or config change | Add a validation rule |
| S | 1-2 | One component or endpoint | Add a new API endpoint |
| M | 3-5 | One feature slice | User registration flow |
| L | 5-8 | Multi-component feature | Search with filtering and pagination |
| XL | 8+ | Too large — break it down further | — |
If a task is L or larger, it should be broken into smaller tasks. An agent performs best on S and M tasks.
When to break a task down further: - It would take more than one focused session (roughly 2+ hours of agent work) - You cannot describe the acceptance criteria in 3 or fewer bullet points - It touches two or more independent subsystems (e.g., auth and billing) - You find yourself writing "and" in the task title (a sign it is two tasks)
tasks/plan.md. This is always a markdown file — design decisions, risks, and open questions don't map cleanly onto individual tracker issues.Create the tasks/ directory if it does not exist.
Never overwrite an incomplete plan. Before writing tasks/plan.md or tasks/todo.md, check whether they already exist and still contain unchecked tasks:
The same rule applies to an external task list target: never bulk-close or delete another plan's open tracker items to make room for new ones.
The task list target is where tasks and checkpoints are recorded. It is defined once, here; every other reference in this skill defers to it.
tasks/todo.md. This is the convention the /build command and other downstream tooling expect. Use it unless the project says otherwise.CLAUDE.md, AGENTS.md, etc.) or the user designate an issue tracker (e.g. GitHub Issues, Jira, Linear, bd/beads), create one tracker item per task instead of writing tasks/todo.md. Map the Step 4 structure onto the tracker's fields: acceptance criteria and verification steps in the item body, dependencies via the tracker's linking mechanism (bd dep add, "blocked by", etc.). Record Step 5 checkpoints as tracker items too, or as a checklist in the plan document if the tracker has no natural equivalent.When using an external tracker, note it in tasks/plan.md (e.g. "Tasks tracked in Linear project FOO") so downstream steps and future sessions know where to look, and keep the plan document's Task List section as an ordered index of tracker item IDs or links rather than a duplicate checklist.
# Implementation Plan: [Feature/Project Name]
## Overview
[One paragraph summary of what we're building]
## Architecture Decisions
- [Key decision 1 and rationale]
- [Key decision 2 and rationale]
## Task List
### Phase 1: Foundation
- [ ] Task 1: ...
- [ ] Task 2: ...
### Checkpoint: Foundation
- [ ] Tests pass, builds clean
### Phase 2: Core Features
- [ ] Task 3: ...
- [ ] Task 4: ...
### Checkpoint: Core Features
- [ ] End-to-end flow works
### Phase 3: Polish
- [ ] Task 5: ...
- [ ] Task 6: ...
### Checkpoint: Complete
- [ ] All acceptance criteria met
- [ ] Ready for review
## Risks and Mitigations
| Risk | Impact | Mitigation |
|------|--------|------------|
| [Risk] | [High/Med/Low] | [Strategy] |
## Open Questions
- [Question needing human input]
When tasks live in an external tracker, keep the Task List section above as an ordered index of tracker item IDs or links instead of a duplicate checklist.
When multiple agents or sessions are available:
| Rationalization | Reality |
|---|---|
| "I'll figure it out as I go" | That's how you end up with a tangled mess and rework. 10 minutes of planning saves hours. |
| "The tasks are obvious" | Write them down anyway. Explicit tasks surface hidden dependencies and forgotten edge cases. |
| "Planning is overhead" | Planning is the task. Implementation without a plan is just typing. |
| "I can hold it all in my head" | Context windows are finite. Written plans survive session boundaries and compaction. |
"The old tasks/plan.md is stale, I'll just replace it" |
Unchecked tasks may be mid-build in another session. Overwriting them destroys work state that exists nowhere else. Stop and ask. |
tasks/plan.md or tasks/todo.md that still has unchecked tasks for different work, without askingtasks/todo.md when the project has designated an external tracker (or scattering tasks across both)Before starting implementation, confirm:
tasks/todo.md)Acceptance criteria are per-task and answer "did we build the right thing?". They sit on top of the project-wide Definition of Done, the standing bar every task clears before it counts as done. See ../../references/definition-of-done.md.
LICENSESKILL.mdVendored from addyosmani/agent-skills, commit aeac41d4d005, path skills/planning-and-task-breakdown, licence MIT. The upstream licence file ships inside the skill.