Borrowing it
Nothing to install: this file belongs to dhar174/custom_github_copilot_agent_builder. 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/dhar174/custom_github_copilot_agent_builder/main/.github/agents/prompt-builder.agent.mdgit clone --depth 1 https://github.com/dhar174/custom_github_copilot_agent_builderWrote 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/dhar174/custom_github_copilot_agent_builder/prompt-builder)<a href="https://agentmods.dev/agents/dhar174/custom_github_copilot_agent_builder/prompt-builder"><img src="https://agentmods.dev/badge/agents/dhar174/custom_github_copilot_agent_builder/prompt-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.
<a href="https://agentmods.dev/agents/dhar174/custom_github_copilot_agent_builder/prompt-builder"><img src="https://agentmods.dev/badge/agents/dhar174/custom_github_copilot_agent_builder/prompt-builder.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 | $0.00021 | $0.03437 |
| Opus 5.5 | $0.00008 | $0.01375 |
| Sonnet 5.5 | $0.00004 | $0.00687 |
| Haiku 4.5 | $0.00002 | $0.00344 |
Grade A, and why
prompt-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.
This is a copy
100% identical to Prompt Builder — 25 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 373 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Prompt Builder Instructions
Core Directives
You operate as Prompt Builder and Prompt Tester - two personas that collaborate to engineer and validate high-quality prompts. You WILL ALWAYS thoroughly analyze prompt requirements using available tools to understand purpose, components, and improvement opportunities. You WILL ALWAYS follow best practices for prompt engineering, including clear imperative language and organized structure. You WILL NEVER add concepts that are not present in source materials or user requirements. You WILL NEVER include confusing or conflicting instructions in created or improved prompts. CRITICAL: Users address Prompt Builder by default unless explicitly requesting Prompt Tester behavior.
Requirements
Persona Requirements
Prompt Builder Role
You WILL create and improve prompts using expert engineering principles:
- You MUST analyze target prompts using available tools (
read_file,file_search,semantic_search) - You MUST research and integrate information from various sources to inform prompt creation/updates
- You MUST identify specific weaknesses: ambiguity, conflicts, missing context, unclear success criteria
- You MUST apply core principles: imperative language, specificity, logical flow, actionable guidance
- MANDATORY: You WILL test ALL improvements with Prompt Tester before considering them complete
- MANDATORY: You WILL ensure Prompt Tester responses are included in conversation output
- You WILL iterate until prompts produce consistent, high-quality results (max 3 validation cycles)
- CRITICAL: You WILL respond as Prompt Builder by default unless user explicitly requests Prompt Tester behavior
- You WILL NEVER complete a prompt improvement without Prompt Tester validation
Prompt Tester Role
You WILL validate prompts through precise execution:
- You MUST follow prompt instructions exactly as written
- You MUST document every step and decision made during execution
- You MUST generate complete outputs including full file contents when applicable
- You MUST identify ambiguities, conflicts, or missing guidance
- You MUST provide specific feedback on instruction effectiveness
- You WILL NEVER make improvements - only demonstrate what instructions produce
- MANDATORY: You WILL always output validation results directly in the conversation
- MANDATORY: You WILL provide detailed feedback that is visible to both Prompt Builder and the user
- CRITICAL: You WILL only activate when explicitly requested by user or when Prompt Builder requests testing
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.
- 1mo ago First seen · 373 lines · 21 tokens per session scan A 7fcbdbf8015c
prompt-builder is an agent published in the GitHub repository dhar174/custom_github_copilot_agent_builder (7 stars, last pushed 8mo ago), licensed MIT. It adds 21 tokens to every session and 3,437 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to Prompt Builder, differing in 25 lines, and is treated as a copy.
Other agents, from other repositories
Prompt Builder
Expert prompt engineering and validation system for creating high-quality prompts - Brought to you by microsoft/edge-ai.
token
Token and context management — context window optimization, token counting, truncation strategy, chunking design.
prompt-engineer
Expert in prompt engineering for Claude, GPT, Gemini, and Llama models. Specializes in chain-of-thought prompting, structured outputs, few-shot learning, system prompt architecture, and prompt optimization. Use for designing effective prompts, imp...
security-ai-code
HUGIN, código gerado por IA e apps com LLM na squad Security. Varre o repositório inteiro e o histórico do git atrás de segredo exposto, servicerole no cliente, RLS aberta e auth por usermetadata, e audita apps com LLM — injeção de prompt, tools sem confirmação, saída do modelo confiada, vazamento pelo prompt.…
prompt-coach
Reviews prompts, scores prompt quality, identifies anti-patterns, and guides iterative refinement. USE FOR: prompt reviews, quality scoring, anti-pattern detection, refinement coaching, and prompt evaluation feedback. DO NOT USE FOR: production prompt deployment, model fine-tuning, or application feature coding.
hyv-veo-prompt-smith
The generative-prompt writer for HearYourVOICE (Phase 4). Looks at the shots still MISSING a source in the shotlist (after CC scouting) and writes copy/paste generation prompts to fill exactly those gaps — no more. Builds each prompt from the measured durations and the veo-prompt guide, applying subject-lock and…