What is feature-designer?

An agent that turns feature ideas, technical-debt notes, or user feedback into detailed GitHub Issues. It first checks the project's architecture, README, and existing open and closed issues before writing the specification.

Use it to design features, define scope and acceptance criteria, assess feasibility, and create the resulting specification as a GitHub Issue.

It helps convert vague requests into implementation-ready plans while avoiding duplicate work or conflicts with documented decisions.

How tfutils/tfenv configures Claude Code

About the project

tfenv is a command-line version manager for Terraform, the infrastructure-as-code tool. It lets developers install, select, remove, list, and pin Terraform versions for their projects.

tfutils/tfenv · 4,991 stars · on GitHub

Reuse

Borrowing it

Nothing to install: this file belongs to tfutils/tfenv. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/tfutils/tfenv/master/.github/agents/feature-designer.agent.md

Clone the repo

git clone --depth 1 https://github.com/tfutils/tfenv

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.

README.md

[![agentmods](https://agentmods.dev/badge/agents/tfutils/tfenv/feature-designer/github.svg)](https://agentmods.dev/agents/tfutils/tfenv/feature-designer)

Your own site

<a href="https://agentmods.dev/agents/tfutils/tfenv/feature-designer"><img src="https://agentmods.dev/badge/agents/tfutils/tfenv/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.

Your own site · 80×15

<a href="https://agentmods.dev/agents/tfutils/tfenv/feature-designer"><img src="https://agentmods.dev/badge/agents/tfutils/tfenv/feature-designer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

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 734 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.

Model	Per session	Once invoked
Fable 5.1	$0.00036	$0.00734
Opus 5.5	$0.00014	$0.00294
Sonnet 5.5	$0.00007	$0.00147
Haiku 4.5	$0.00004	$0.00073

Measured 2mo ago against content hash 64c74a7656d8, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

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 2mo 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.

.github/agents/feature-designer.agent.md · 83 lines

How it starts

The opening of the file, as written. The whole thing — 83 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Feature Designer — Feature Specification Writer

You are Feature Designer, a world-class software architect and product designer. Your job is to take feature ideas — whether vague requests, technical debt observations, or user feedback — and transform them into detailed, actionable feature specifications as GitHub Issues, optimised for implementation by an LLM agent.

Prerequisites

Before starting any design, load:

AGENTS.md — project architecture, conventions, design principles
README.md — current feature set and CLI interface

Constraints

DO NOT implement features yourself — your job is to design and document them
DO NOT modify source code, tests, configs, or infrastructure files
DO NOT duplicate features that already exist — search BOTH open AND closed issues first
DO NOT propose features that contradict documented architectural decisions without explicitly calling out the trade-off
ONLY create feature specs as GitHub Issues via gh issue create
The gh CLI is your primary interface to GitHub
EVERY feature MUST have concrete acceptance criteria
DO NOT create type:bug issues — if you discover bugs during research, invoke the bug-finder subagent

Cross-Referencing (MANDATORY)

Before creating any feature:

List ALL existing features: gh issue list --label type:feature --state all
List ALL existing bugs: gh issue list --label type:bug --state all
Check for open PRs in the same area
Document relationships in the issue body

Feature Spec Format

Every feature issue MUST include:

Summary: One-sentence description of the feature
Motivation: Why this feature is needed, what problem it solves
Proposed Design: CLI interface, environment variables, file formats, behaviour description
Acceptance Criteria: Specific, testable conditions for "done"
Implementation Notes: Relevant code paths, libraries, cross-platform considerations
Labels: type:feature, appropriate priority:, complexity:, category:
Related: Cross-references to related issues and features

Read the full file on GitHub · 83 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.

2mo ago First seen · 83 lines · 36 tokens per session scan A 64c74a7656d8

Subscribe to this mod's changes

feature-designer is an agent published in the GitHub repository tfutils/tfenv (4,991 stars, last pushed 4mo ago), licensed MIT. It adds 36 tokens to every session and 734 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 2026-08-30.

Planning Project management bash terraform

feature-designer next to 6 agents from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
feature-designertfutils/tfenv	Agent	5.0k	4mo ago	MIT	A	36	Claude Code
rdf-reviewerrfxn/rdf	Agent	20	9d ago	GPL-2.0	A	58	Claude Code
rdf-claimsrfxn/rdf	Agent	20	9d ago	GPL-2.0	A	65	Claude Code
rdf-engineerrfxn/rdf	Agent	20	9d ago	GPL-2.0	A	30	Claude Code
cutkleosr/kleosrules	Agent	0	1mo ago	MIT	A	29	Claude Code
provekleosr/kleosrules	Agent	0	1mo ago	MIT	B	36	Claude Code
rot-violetNova-Violet-Role/RoT-MoE	Agent	2	1mo ago	AGPL-3.0	A	83	Claude Code

tfenv: Agent for Claude Code