# Planning And Task Breakdown

> Breaks work into ordered tasks. Use when you have a spec or clear requirements and need to break work into implementable tasks. Use when a task feels too large to start, when you need to estimate scope, or when parallel work is possible.

- Skill: `jmxt3/planning-and-task-breakdown` (Agent Skill)
- Install (CLI): `npx skillmds@latest add jmxt3/planning-and-task-breakdown`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jmxt3/planning-and-task-breakdown/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Productivity
- Author: jmxt3 (https://skillmd.com/u/jmxt3)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/jmxt3/planning-and-task-breakdown

---


# Planning and Task Breakdown

## Overview

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 to Use

- You have a spec and need to break it into implementable units
- A task feels too large or vague to start
- Work needs to be parallelized across multiple agents or sessions
- You need to communicate scope to a human
- The implementation order isn't obvious

**When NOT to use:** Single-file changes with obvious scope, or when the spec already contains well-defined tasks.

## The Planning Process

### Step 1: Enter Plan Mode

Before writing any code, operate in read-only mode:

- Read the spec and relevant codebase sections
- Identify existing patterns and conventions
- Map dependencies between components
- Note risks and unknowns

**Do NOT write code during planning.** The output is a plan document, not implementation.

### Step 2: Identify the Dependency Graph

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.

### Step 3: Slice Vertically

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 export a skill (skill schema + API + UI for export)
```

Each vertical slice delivers working, testable functionality.

### Step 4: Write Tasks

Each task follows this structure:

```markdown
## Task [N]: [Short descriptive title]

**Description:** One paragraph explaining what this task accomplishes.

**Acceptance criteria:**
- [ ] [Specific, testable condition]
- [ ] [Specific, testable condition]

**Verification:**
- [ ] Tests pass: `pytest tests/ -k "test_name"`
- [ ] Build succeeds
- [ ] Manual check: [description of what to verify]

**Dependencies:** [Task numbers this depends on, or "None"]

**Files likely touched:**
- `api/app/path/to/file.py`
- `web/components/path/to/component.tsx`

**Estimated scope:** [Small: 1-2 files | Medium: 3-5 files | Large: 5+ files]
```

### Step 5: Order and Checkpoint

Arrange tasks so that:

1. Dependencies are satisfied (build foundation first)
2. Each task leaves the system in a working state
3. Verification checkpoints occur after every 2-3 tasks
4. High-risk tasks are early (fail fast)

Add explicit checkpoints:

```markdown
## Checkpoint: After Tasks 1-3
- [ ] All tests pass
- [ ] Application builds without errors
- [ ] Core user flow works end-to-end
- [ ] Review with human before proceeding
```

## Task Sizing Guidelines

| 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 | Skill export 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, break it 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
- You cannot describe the acceptance criteria in 3 or fewer bullet points
- It touches two or more independent subsystems
- You find yourself writing "and" in the task title

## Common Rationalizations

| 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. |

## Red Flags

- Starting implementation without a written task list
- Tasks that say "implement the feature" without acceptance criteria
- No verification steps in the plan
- All tasks are XL-sized
- No checkpoints between tasks
- Dependency order isn't considered

## Verification

Before starting implementation, confirm:

- [ ] Every task has acceptance criteria
- [ ] Every task has a verification step
- [ ] Task dependencies are identified and ordered correctly
- [ ] No task touches more than ~5 files
- [ ] Checkpoints exist between major phases
- [ ] The human has reviewed and approved the plan