plan-creator

A command for writing detailed architectural plans for new features in existing codebases. It explains how the feature should be implemented and can use design documents or code maps as context.

In plain words
What is it for?
Use it to plan additions such as login, user profiles, caching, or refactors in an existing project.
Why use it?
It turns a feature request into an implementation plan and identifies missing decisions before coding starts.

Command

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/gantisstorm/essentials-claude-code/plan-creator
Clone the repo
git clone --depth 1 https://github.com/GantisStorm/essentials-claude-code
Per session 36 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 797 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00036 $0.00797
Opus 5 $0.00018 $0.00398
Sonnet 5 $0.00007 $0.00159
Haiku 4.5 $0.00004 $0.00080

Measured 2d ago against content hash 8cbbb8862d1f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

plan-creator scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

essentials/commands/plan-creator.md · 100 lines

How it starts

The opening of the file, as written. The whole thing — 100 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Architectural Plan Creator

Create comprehensive architectural plans for new features in existing codebases (brownfield development). Plans specify HOW to implement, not just WHAT.

Use the right tool:

  • New features/enhancements/plan-creator (this command)
  • Bug fixes/bug-plan-creator
  • Code quality improvements/code-quality-plan-creator

Arguments

Takes a feature description and optional reference material:

  • "Add OAuth2 authentication with Google login"
  • "Add user profile page with avatar upload"
  • "Refactor auth module to use dependency injection"
  • "Add caching layer" .claude/maps/code-map-src-a3f9e.json — pass a code map, design doc, or any file as additional context

Instructions

Step 1: Process Input

Parse $ARGUMENTS as the task description. Grammar and spell check before passing to agent.

Step 2: Ask Clarifying Questions

Use AskUserQuestion to gather missing context. Ask only what's unclear — skip questions the user already answered in their input.

Questions to consider (ask 1-4 based on what's missing):

  • Scope: Which parts of the codebase should this touch? Any areas off-limits?
  • Constraints: Any specific tech, patterns, or libraries to use or avoid?
  • Behavior: Key edge cases, error handling, or user-facing behaviors to get right?
  • Exit criteria: How will we verify it works? Specific test commands, endpoints to hit, or behaviors to check?

If the input is already detailed enough (clear scope, obvious constraints, well-defined behavior), skip this step entirely and go straight to Step 3.

Step 3: Launch Agent

Assemble the enriched prompt from the original description + clarifying answers. Launch background agent:

Create architectural plan:

Task: <corrected task description>

<clarifying context from user answers, if any>
<reference material contents, if any>

REQUIRED Task tool parameters:

subagent_type: "essentials:plan-creator-default"
run_in_background: true
prompt: "<assembled prompt with all context>"

Read the full file on GitHub · 100 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 100 lines · 36 tokens per session scan A 8cbbb8862d1f

Subscribe to this mod's changes

plan-creator is a command published in the GitHub repository GantisStorm/essentials-claude-code (91 stars, last pushed 6mo ago), licensed Unlicense. It adds 36 tokens to every session and 797 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.