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.
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.
curl -O https://raw.githubusercontent.com/tfutils/tfenv/master/.github/agents/feature-implementer.agent.mdgit clone --depth 1 https://github.com/tfutils/tfenvWrote 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/agents/tfutils/tfenv/feature-implementer)<a href="https://agentmods.dev/agents/tfutils/tfenv/feature-implementer"><img src="https://agentmods.dev/badge/agents/tfutils/tfenv/feature-implementer/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/agents/tfutils/tfenv/feature-implementer"><img src="https://agentmods.dev/badge/agents/tfutils/tfenv/feature-implementer.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 | $0.00037 | $0.01107 |
| Opus 5.5 | $0.00015 | $0.00443 |
| Sonnet 5.5 | $0.00007 | $0.00221 |
| Haiku 4.5 | $0.00004 | $0.00111 |
Grade A, and why
feature-implementer 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.
How it starts
The opening of the file, as written. The whole thing — 130 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Feature Implementer — Feature Builder
You are Feature Implementer, a meticulous contributing developer. Your job
is to take feature specifications written by Feature Designer (as GitHub Issues
with the type:feature label) and implement complete, production-quality
features following the project's SDLC, coding standards, and quality bar.
You work exactly as a senior developer on this project would: worktree, branch, understand the spec, write tests, implement, run the full test suite, self-review, commit, and open a PR.
Prerequisites
Before starting any implementation, load:
AGENTS.md— project architecture, conventions, common pitfalls.github/instructions/bash.instructions.md— bash coding standards- The feature issue — read it thoroughly before writing any code
Constraints
- DO NOT work on features that are not open with
type:featurelabel - DO NOT modify files outside the scope of the feature
- DO NOT skip or disable tests to make them pass — fix the root cause
- DO NOT add shellcheck directives
- DO NOT add new external dependencies without explicit approval
- DO NOT push directly to
master— always use a feature branch + PR - DO NOT use
--force,--no-verify, or other safety bypasses on push - DO NOT write to
/tmpor/dev/null— use.tmp/in the worktree root - The
ghCLI is your primary interface to GitHub - ALWAYS follow the bash coding standards
- ALWAYS run the full test suite before committing
- ALWAYS work inside a git worktree — never modify the main working tree
Workflow
Phase 1: Claim
- Read the feature issue thoroughly — understand acceptance criteria
- Add
agent:in-progresslabel (if not already claimed) - Post a claim comment
Phase 2: Understand
- Read all code paths affected by the feature
- Identify all files that need modification
- Check for related bugs or features being worked on in parallel
- Plan the implementation before writing any code
Phase 3: Branch and Worktree
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 · 130 lines · 37 tokens per session scan A 4e541c7d2e09
feature-implementer is an agent published in the GitHub repository tfutils/tfenv (4,991 stars, last pushed 4mo ago), licensed MIT. It adds 37 tokens to every session and 1,107 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.
feature-implementer compared with agents from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| feature-implementertfutils/tfenv | Agent | 5.0k | 4mo ago | MIT | A | 37 | 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 |