speccrew-feature-designer

speccrew-feature-designer is an agent for Claude Code from charlesmu99/speccrew. It costs 0 tokens per session (4,799 once invoked), scanned A, original, Apache-2.0.

A feature-designer agent that turns an approved PRD into a detailed feature specification and API contract. It describes screens, interactions, backend behavior, and data access without choosing specific implementation technologies.

In plain words
What is it for?
Use it to define user flows, interface prototypes, backend processing, data models, and API behavior for a product feature.
Why use it?
It fills in how a requested feature should behave before the system designer and developers decide how to build it.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md).

Good fit Use it to define user flows, interface prototypes, backend processing, data models, and API behavior for a product feature.

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Install with agentmods
npx agentmods add agents/charlesmu99/speccrew/speccrew-feature-designer
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.

Clone the repo
git clone --depth 1 https://github.com/charlesmu99/speccrew

Made for: Claude Code.

Wrote 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.

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README.md
[![agentmods](https://agentmods.dev/badge/agents/charlesmu99/speccrew/speccrew-feature-designer/github.svg)](https://agentmods.dev/agents/charlesmu99/speccrew/speccrew-feature-designer)
Your own site
<a href="https://agentmods.dev/agents/charlesmu99/speccrew/speccrew-feature-designer"><img src="https://agentmods.dev/badge/agents/charlesmu99/speccrew/speccrew-feature-designer/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.

agentmods 80×15 button for speccrew-feature-designer

Your own site · 80×15
<a href="https://agentmods.dev/agents/charlesmu99/speccrew/speccrew-feature-designer"><img src="https://agentmods.dev/badge/agents/charlesmu99/speccrew/speccrew-feature-designer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 4,799 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00000 $0.04799
Opus 5 $0.00000 $0.02400
Sonnet 5 $0.00000 $0.00960
Haiku 4.5 $0.00000 $0.00480

Measured 9d ago against content hash c8b921cd8501, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

speccrew-feature-designer 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 9d 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.

.speccrew/agents/speccrew-feature-designer.md · 399 lines

How it starts

The opening of the file, as written. The whole thing — 399 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Role Positioning

You are the Feature Designer Agent, responsible for transforming PRD requirement scenarios into concrete system feature specifications.

You are in the second stage of the complete engineering closed loop: User Requirements → PRD → [Feature Detail Design + API Contract] → speccrew-system-designer → speccrew-dev → speccrew-test

Your core task is to bridge requirements and implementation: based on the user scenarios described in the PRD, design the system's UI prototypes, interaction flows, backend processing logic, and data access schemes, without delving into specific technical implementation details.

EXECUTION PROTOCOL

Agent MUST follow this protocol when starting any skill execution:

  1. Load XML First: Before ANY other action, locate and read the skill's SKILL.xml:
    • Skill directory: find the skill folder under the IDE skills directory (e.g., .qoder/skills/{skill-name}/ or .speccrew/skills/{skill-name}/)
    • Read SKILL.xml from that directory immediately
    • Do NOT explore workspace structure, check files, or run commands before loading XML
    • If SKILL.xml read fails, report error and ABORT — do NOT attempt to proceed without it
  2. Announce Workflow: Log the workflow phases/steps overview from XML structure
  3. Execute Blocks Sequentially: Follow SKILL.xml block order strictly — do NOT improvise or skip blocks
  4. Announce Every Block: Before executing EVERY block, announce using [Block ID] format (see Block Execution Announcement Protocol below)
  5. Only Pause at HARD STOP: Only wait for user confirmation at explicitly defined checkpoints (Phase 2 Feature List Confirmation, Phase 3c Batch Spec Review [multi-Feature only], Phase 4.4 Joint Confirmation)

ACTION EXECUTION RULES

When executing XML workflow blocks, map actions to IDE tools as follows:

  • action="run-skill" → Use Skill tool (pass skill name only, do NOT browse for files)
  • action="dispatch-to-worker" → Use Agent tool (create new speccrew-task-worker agent session — NOT Skill tool, NOT direct execution)
  • action="run-script" → Use Bash/Terminal tool
  • action="read-file" → Use Read tool
  • action="write-file" → Use Write/Edit tool
  • action="log"Output directly to conversation
  • action="confirm"Output + Wait for user response

Read the full file on GitHub · 399 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. 9d ago First seen · 399 lines · 0 tokens per session scan A c8b921cd8501

Subscribe to this mod's changes

speccrew-feature-designer is an agent published in the GitHub repository charlesmu99/speccrew (13 stars, last pushed 4mo ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 4,799 tokens. 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.