Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add sequenzia/claude-plugins/plugin install dev-toolsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/commands/sequenzia/claude-plugins/feature-dev)<a href="https://agentmods.dev/commands/sequenzia/claude-plugins/feature-dev"><img src="https://agentmods.dev/badge/commands/sequenzia/claude-plugins/feature-dev/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/commands/sequenzia/claude-plugins/feature-dev"><img src="https://agentmods.dev/badge/commands/sequenzia/claude-plugins/feature-dev.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00013 | $0.02539 |
| Opus 5.5 | $0.00005 | $0.01016 |
| Sonnet 5.5 | $0.00003 | $0.00508 |
| Haiku 4.5 | $0.00001 | $0.00254 |
Grade A, and why
feature-dev 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 358 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Feature Development Workflow
You are executing a structured 7-phase feature development workflow. This workflow guides you through understanding, exploring, designing, implementing, and reviewing a feature.
CRITICAL: You MUST complete ALL 7 phases. The workflow is not complete until Phase 7: Summary is finished. After completing each phase, immediately proceed to the next phase without waiting for user prompts.
Phase Overview
Execute these phases in order, completing ALL of them:
- Discovery - Understand the feature requirements
- Codebase Exploration - Map relevant code areas
- Clarifying Questions - Resolve ambiguities
- Architecture Design - Design the implementation approach
- Implementation - Build the feature
- Quality Review - Review for issues
- Summary - Document accomplishments
Phase 1: Discovery
Goal: Understand what the user wants to build.
-
Create a TodoWrite entry for each phase:
- Phase 1: Discovery - Phase 2: Codebase Exploration - Phase 3: Clarifying Questions - Phase 4: Architecture Design - Phase 5: Implementation - Phase 6: Quality Review - Phase 7: Summary -
Mark Phase 1 as
in_progress -
Analyze the feature description:
- What is the core functionality?
- What are the expected inputs and outputs?
- Are there any constraints mentioned?
- What success criteria can you infer?
-
Summarize your understanding to the user. Ask if your understanding is correct before proceeding.
-
Mark Phase 1 as
completed
Phase 2: Codebase Exploration
Goal: Understand the relevant parts of the codebase.
-
Mark Phase 2 as
in_progress -
Load skills for this phase:
- Read
${CLAUDE_PLUGIN_ROOT}/skills/project-conventions/SKILL.mdand apply its guidance - Read
${CLAUDE_PLUGIN_ROOT}/skills/language-patterns/SKILL.mdand apply its guidance
- Read
-
Launch code-explorer agents:
Launch 2-3 code-explorer agents in parallel with different focus areas:
Agent 1: Explore entry points and user-facing code related to the feature Agent 2: Explore data models, schemas, and storage related to the feature Agent 3: Explore utilities, helpers, and shared infrastructure (if applicable)
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.
- 1mo ago First seen · 358 lines · 13 tokens per session scan A 9912f0b1c786
feature-dev is a command published in the GitHub repository sequenzia/claude-plugins (2 stars, last pushed 8mo ago), licensed MIT. It adds 13 tokens to every session and 2,539 once invoked, about $0.0001 per session on Opus 5.5. 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.
Other commands, from other repositories
checklist
Generate a custom checklist for the current feature based on user requirements.
clarify
Identify underspecified areas in the current feature spec by asking up to 5 highly targeted clarification questions and encoding answers back into the spec.
specify
Create or update the feature specification from a natural language feature description.
converge
Assess the current codebase against the feature's spec, plan, and tasks, then append any remaining unbuilt work as new tasks to tasks.md so implement can complete it.
implement
Execute the implementation plan by processing and executing all tasks defined in tasks.md.
speckit.bug.fix
Apply the remediation from a bug assessment and record what was changed.