spec

A command for starting a feature-development process based on a written specification. It gathers requirements, then creates the design, implementation tasks, and validation steps.

In plain words
What is it for?
Use it when a feature needs requirements, a design, a task list, and a review that checks whether the planned work is complete and consistent.
Why use it?
Starting with a specification helps clarify what should be built before coding begins. It also separates requirement gathering, design, task planning, and checking into defined stages.

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/habib0x0/spec-driven-plugin/spec
Clone the repo
git clone --depth 1 https://github.com/Habib0x0/spec-driven-plugin
Per session 12 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,409 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 $0.00012 $0.03409
Opus 5 $0.00006 $0.01705
Sonnet 5 $0.00002 $0.00682
Haiku 4.5 $0.00001 $0.00341

Measured 2d ago against content hash cabfff2ceb74, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

spec 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.

commands/spec.md · 280 lines

How it starts

The opening of the file, as written. The whole thing — 280 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/spec Command

Create a new specification for a feature using the 3-phase spec-driven workflow. Requirements are gathered interactively with the user, then agents handle the heavy writing.

Model Routing

Phase Who Model Tier Why
Phase 0 Scan spec-scanner agent standard Fast multi-file reading; reasoning depth not critical
Requirements Gathering /spec command (inline) Current model Interactive — needs AskUserQuestion
Requirements + Design Writing spec-planner agent reasoning Deep reasoning for edge cases and architecture
Tasks spec-tasker agent standard Fast, structured task generation
Validation spec-validator agent standard Checklist-based verification

Model Override

Each agent spawn below reads a SPEC_MODEL_* environment variable. When the variable is set and non-empty, pass its value as the model: parameter to the Task tool, overriding the agent's frontmatter tier alias. When unset, omit model: from the Task invocation and the agent runs on its frontmatter default.

Env var Agent Default tier
SPEC_MODEL_SCANNER spec-scanner standard
SPEC_MODEL_PLANNER spec-planner reasoning
SPEC_MODEL_TASKER spec-tasker standard
SPEC_MODEL_VALIDATOR spec-validator standard

Example spawn with override: Task(subagent_type="spec-planner", model="$SPEC_MODEL_PLANNER", prompt=...) when SPEC_MODEL_PLANNER is set. See docs/advanced/model-routing.md for full details.

Arguments

  • feature-name (required): Name for the feature spec (kebab-case recommended)

Workflow

1. Initialize Spec Directory

Create the spec directory structure:

.claude/specs/<feature-name>/
├── requirements.md
├── design.md
└── tasks.md

Use templates from ${CLAUDE_PLUGIN_ROOT}/templates/ as starting points. Copy each template to the spec directory.

1.5. Phase 0: Project Profile Check

Before gathering requirements, check for (or create) a project profile so that downstream agents have codebase context.

Read the full file on GitHub · 280 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 · 280 lines · 12 tokens per session scan A cabfff2ceb74

Subscribe to this mod's changes

spec is a command published in the GitHub repository Habib0x0/spec-driven-plugin (10 stars, last pushed 3mo ago), licensed MIT. It adds 12 tokens to every session and 3,409 once invoked, about $0.0001 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 2026-08-31.