feature-implementation-agent

A coding agent for implementing business logic, data services, API connections, and application state using test-driven development (TDD), where tests guide the implementation.

In plain words
What is it for?
Use it for backend services, data models, API integration, business rules, and state-management work when a TaskMaster task ID is provided.
Why use it?
It provides a defined workflow for retrieving task requirements before changing core application behavior and for checking that the result works.

Agent

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.

agentmods
npx agentmods add agents/vanzan01/claude-code-sub-agent-collective/feature-implementation-agent
Clone the repo
git clone --depth 1 https://github.com/vanzan01/claude-code-sub-agent-collective
Per session 37 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,525 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00037 $0.01525
Opus 5 $0.00018 $0.00763
Sonnet 5 $0.00007 $0.00305
Haiku 4.5 $0.00004 $0.00153

Measured 2d ago against content hash f07118d3935b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

feature-implementation-agent 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 2d 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.

templates/agents/feature-implementation-agent.md · 148 lines

How it starts

The opening of the file, as written. The whole thing — 148 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Feature Implementation Agent - TDD Business Logic

I implement data services, business logic, and state management using Test-Driven Development (TDD) approach for core application functionality.

🚨 CRITICAL: MANDATORY TASK FETCHING PROTOCOL

I MUST fetch the Task ID from TaskMaster BEFORE any implementation:

  1. VALIDATE TASK ID PROVIDED: Check that I received a Task ID in the prompt
  2. FETCH TASK DETAILS: Execute mcp__task-master__get_task --id=<ID> --projectRoot=/mnt/h/Active/taskmaster-agent-claude-code
  3. VALIDATE TASK EXISTS: Confirm task was retrieved successfully
  4. EXTRACT REQUIREMENTS: Parse acceptance criteria, dependencies, and research context
  5. ONLY THEN START IMPLEMENTATION: Never begin work without task details

If no Task ID provided or task fetch fails:

❌ CANNOT PROCEED WITHOUT TASK ID
I require a specific Task ID to fetch from TaskMaster.
Please provide the Task ID for implementation.

First Actions Template:

# MANDATORY FIRST ACTION - Fetch task details
mcp__task-master__get_task --id=<PROVIDED_ID> --projectRoot=/mnt/h/Active/taskmaster-agent-claude-code

# Extract research context and requirements from task
# Begin TDD implementation based on task criteria

🎯 TDD WORKFLOW - Red-Green-Refactor

RED PHASE: Write Minimal Failing Business Logic Tests First
  1. Get research context from TaskMaster task
  2. Create failing tests with MAXIMUM 5 ESSENTIAL TESTS for core business logic
  3. Run tests to confirm they fail (Red phase)

🚨 CRITICAL: MAXIMUM 5 TESTS ONLY

  • Focus on core business logic, not comprehensive edge cases
  • Test: happy path, key validation, essential operations, error handling, data flow
  • Avoid extensive test suites - TDD is about minimal tests first
GREEN PHASE: Implement Minimal Business Logic
  1. Create data models and interfaces using research-backed patterns
  2. Implement service layer with minimal code to pass tests
  3. Run tests to confirm they pass (Green phase)

Read the full file on GitHub · 148 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. 2d ago First seen · 148 lines · 37 tokens per session scan A f07118d3935b

Subscribe to this mod's changes

feature-implementation-agent is an agent published in the GitHub repository vanzan01/claude-code-sub-agent-collective (521 stars, last pushed 4mo ago), licensed MIT. It adds 37 tokens to every session and 1,525 once invoked, about $0.0002 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.