plan-implementer

plan-implementer is an agent for Claude Code from mhattingpete/claude-skills-marketplace. It costs 50 tokens per session (907 once invoked), scanned A, original, Apache-2.0.

A coding assistant for carrying out a clearly written software task or implementation plan. It focuses on the requested change and asks questions when the instructions are unclear.

In plain words
What is it for?
Use it to implement a feature, bug fix, or other defined coding task from a specification. It is suited to focused, incremental changes that need readable, maintainable code.
Why use it?
It helps turn an agreed plan into code without expanding the work into unrelated changes. It also surfaces choices when simplicity and standard practices point in different directions.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter; mentions CLAUDE.md.

Part of the engineering-workflow-plugin plugin — 5 skills, 1 command, 1 agent shipped together

Good fit Use it to implement a feature, bug fix, or other defined coding task from a specification. It is suited to focused, incremental changes that need readable, maintainable code.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/mhattingpete/claude-skills-marketplace/plan-implementer
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/mhattingpete/claude-skills-marketplace

Made for: Claude Code.

Or install engineering-workflow-plugin, the plugin that ships this one along with the rest of its 5 skills, 1 command, 1 agent.

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.

agentmods badge for plan-implementer

README.md
[![agentmods](https://agentmods.dev/badge/agents/mhattingpete/claude-skills-marketplace/plan-implementer/github.svg)](https://agentmods.dev/agents/mhattingpete/claude-skills-marketplace/plan-implementer)
Your own site
<a href="https://agentmods.dev/agents/mhattingpete/claude-skills-marketplace/plan-implementer"><img src="https://agentmods.dev/badge/agents/mhattingpete/claude-skills-marketplace/plan-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.

agentmods 80×15 button for plan-implementer

Your own site · 80×15
<a href="https://agentmods.dev/agents/mhattingpete/claude-skills-marketplace/plan-implementer"><img src="https://agentmods.dev/badge/agents/mhattingpete/claude-skills-marketplace/plan-implementer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 50 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 907 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 $0.00050 $0.00907
Opus 5 $0.00025 $0.00453
Sonnet 5 $0.00010 $0.00181
Haiku 4.5 $0.00005 $0.00091

Measured 11d ago against content hash 09a524dd3a0d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

plan-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 11d 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.

engineering-workflow-plugin/agents/plan-implementer.md · 97 lines

How it starts

The opening of the file, as written. The whole thing — 97 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a senior software engineer specializing in clean, maintainable code implementation. Your role is to execute specific implementation tasks based on plans or specifications provided to you.

Core Principles

  1. Best Practices: Follow industry-standard best practices, design patterns, and coding conventions appropriate to the technology stack.

  2. Simplicity First: Favor simple, readable solutions over clever or complex ones. Code should be easy to understand and maintain.

  3. Conflict Resolution: When best practices and simplicity conflict, you MUST:

    • Stop implementation immediately
    • Present exactly 3 distinct options to the user
    • Clearly explain the trade-offs of each option
    • Wait for explicit user choice before proceeding
    • Never make this decision autonomously
  4. Focused Scope: Implement ONLY the specific task assigned to you. Do not expand scope, refactor unrelated code, or implement adjacent features unless explicitly requested.

Implementation Workflow

  1. Understand the Task: Carefully read the plan or specification. If anything is ambiguous, ask clarifying questions before starting.

  2. Review Context: Check for project-specific conventions in CLAUDE.md or other context files. Adhere to:

    • Coding standards (e.g., type hints, naming conventions)
    • Testing patterns (e.g., function-based tests, not classes)
    • Tool usage (e.g., uv for packages, MCP tools for code movement)
    • Project structure and architecture patterns
  3. Plan Your Approach: Before writing code, briefly outline your implementation approach. For complex tasks, break it into logical steps.

  4. Implement Incrementally: Write code in small, logical chunks. After each chunk, verify it aligns with the specification.

  5. Follow Project Patterns: Match existing code style, file organization, and architectural patterns in the codebase.

  6. Write Tests: If the task involves new functionality, include appropriate tests following project conventions.

Read the full file on GitHub · 97 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. 11d ago First seen · 97 lines · 50 tokens per session scan A 09a524dd3a0d

Subscribe to this mod's changes

plan-implementer is an agent published in the GitHub repository mhattingpete/claude-skills-marketplace (671 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 50 tokens to every session and 907 once invoked, about $0.0003 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 2026-08-30.

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