agent-builder

agent-builder is an agent for Claude Code from SteveGJones/ai-first-sdlc-practices. It costs 31 tokens per session (7,011 once invoked), scanned A, original, MIT.

An agent for designing and checking other AI agents from research documents. It turns documented findings into instructions, chooses a suitable agent design, and validates the result.

In plain words
What is it for?
Use it to create or rebuild production agents, distil research into agent instructions, choose an agent structure, and check the finished agent against defined standards.
Why use it?
It gives agent-building work a repeatable process and keeps instructions tied to research evidence instead of assumptions. It also helps detect common design mistakes.

Agent for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: model in frontmatter.

Part of the sdlc-team-common plugin — 8 agents shipped together

Good fit Use it to create or rebuild production agents, distil research into agent instructions, choose an agent structure, and check the finished agent against defined standards.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/stevegjones/ai-first-sdlc-practices/agent-builder
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/SteveGJones/ai-first-sdlc-practices

Made for: Claude Code.

Or install sdlc-team-common, the plugin that ships this one along with the rest of its 8 agents.

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 agent-builder

README.md
[![agentmods](https://agentmods.dev/badge/agents/stevegjones/ai-first-sdlc-practices/agent-builder/github.svg)](https://agentmods.dev/agents/stevegjones/ai-first-sdlc-practices/agent-builder)
Your own site
<a href="https://agentmods.dev/agents/stevegjones/ai-first-sdlc-practices/agent-builder"><img src="https://agentmods.dev/badge/agents/stevegjones/ai-first-sdlc-practices/agent-builder/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 agent-builder

Your own site · 80×15
<a href="https://agentmods.dev/agents/stevegjones/ai-first-sdlc-practices/agent-builder"><img src="https://agentmods.dev/badge/agents/stevegjones/ai-first-sdlc-practices/agent-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 31 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 7,011 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 $0.00031 $0.07011
Opus 5.5 $0.00012 $0.02804
Sonnet 5.5 $0.00006 $0.01402
Haiku 4.5 $0.00003 $0.00701

Measured 1mo ago against content hash d1e2e5590a64, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

agent-builder 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 1mo 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.

plugins/sdlc-team-common/agents/agent-builder.md · 388 lines

How it starts

The opening of the file, as written. The whole thing — 388 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent Builder

You are the Agent Builder, the specialist responsible for constructing production-quality AI agents from research synthesis documents. You orchestrate the full 6-phase construction pipeline: analyzing research inputs, selecting and customizing reference archetypes, distilling domain knowledge into effective LLM instructions, and validating the finished agent against pipeline standards. Your approach is methodical and research-grounded -- every instruction you write in an agent must trace back to a specific research finding, not generic intuition.

Core Competencies

  1. Knowledge Distillation: Transforming research documents into LLM-optimized instructions using the 4-stage Extract-Compress-Contextualize-Validate pipeline and the 30/50/20 content ratio rule
  2. Archetype Selection: Choosing from the 5 reference archetypes (Domain Expert, Architect, Reviewer, Orchestrator, Enforcer) based on the agent's primary function, including hybrid agent design
  3. Anti-Pattern Detection: Identifying and preventing the 12 known agent construction anti-patterns (Platitude Agent, Scope Creep, Template Artifact, etc.)
  4. YAML Frontmatter Engineering: Writing discoverable agent metadata with effective semantic trigger examples that follow the format spec constraints. When the pipeline-orchestrator's discovery phase found official tools, includes first_party_alternatives field listing discovered tools with name, type, and URL.
  5. Structured Instruction Design: Organizing agent content using the role-competencies-process-boundaries pattern with attention to primacy/recency effects
  6. Validation Pipeline Execution: Running automated checks with validate-agent-pipeline.py and manual quality gates (could-be-anyone test, specificity scoring, scenario simulation)
  7. Research-to-Agent Traceability: Ensuring every domain-specific claim in the agent traces to the research synthesis, preventing abstraction drift during distillation

Workflow Phases

Read the full file on GitHub · 388 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. 1mo ago First seen · 388 lines · 31 tokens per session scan A d1e2e5590a64

Subscribe to this mod's changes

agent-builder is an agent published in the GitHub repository SteveGJones/ai-first-sdlc-practices (41 stars, last pushed 15d ago), licensed MIT. It adds 31 tokens to every session and 7,011 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 2026-09-03.

Related

Other agents, from other repositories

Demonstrate

Agent for demonstrating VS Code features.

microsoft/vscode · 10 tokens

playwright-test-generator

Use this agent when you need to create automated browser tests using Playwright Examples: Context: User wants to generate a test for the test plan item.

microsoft/playwright · 151 tokens

.NET-Notebook-Migration-Agent

Expert .NET and documentation transformation agent that migrates Polyglot Jupyter notebooks into clean Markdown and companion .NET sample code.

microsoft/ai-agents-for-beginners · 33 tokens

AVM Owner Triage

Triage open GitHub issues across the Azure Verified Modules (AVM) repos an owner maintains. Splits the backlog into a Copilot-delegatable pile and a human pile, produces a report with a delegation ratio, and never comments or assigns without explicit user approval.

github/awesome-copilot · 61 tokens

Ultimate Transparent Thinking Beast Mode

Agent "Ultimate Transparent Thinking Beast Mode" from github/awesome-copilot, covering quantum cognitive architecture, phase 2: adversarial intelligence & red-team analysis, phase 3: implementation & iterative refinement and phase 4: comprehensive verification & completion.

github/awesome-copilot · 11 tokens

code-reviewer

Performs thorough code reviews for the Notebooks in the Cookbook repo, focusing on Python/Jupyter best practices, and project-specific standards. Use this agent proactively after writing any significant code changes, especially when modifying notebooks, Github Actions, and scripts.

anthropics/claude-cookbooks · 52 tokens