workflow-prompt-writer

workflow-prompt-writer is an agent for Claude Code from growthxai/output. It costs 42 tokens per session (4,963 once invoked), scanned B, original, Apache-2.0.

A specialist guide for writing and checking .prompt files used by the Output SDK. These files combine model settings with message templates, and may use Liquid, a template language for inserting values and controlling repeated or conditional text.

In plain words
What is it for?
Use it when creating, reviewing, or debugging Output SDK prompts, including YAML settings, Liquid templates, multi-turn messages, and structured outputs.
Why use it?
It helps avoid errors in prompt-file structure, template syntax, provider settings, and generated output instructions. It also explains how prompts connect to skills and agents.

Agent for Claude Code

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

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is See [`output-dev-model-selection`](../skills/output-dev-model-selection/SKILL.md) for the canonical decision tree (priority → provider → live AI Gateway lookup .

Part of the outputai plugin — 50 skills, 5 agents, 1 hook shipped together

Good fit Use it when creating, reviewing, or debugging Output SDK prompts, including YAML…

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Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/growthxai/output
agentmods
npx agentmods add agents/growthxai/output/workflow_prompt_writer

Made for: Claude Code.

Or install outputai, the plugin that ships this one along with the rest of its 50 skills, 5 agents, 1 hook.

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 workflow-prompt-writer

README.md
[![agentmods](https://agentmods.dev/badge/agents/growthxai/output/workflow_prompt_writer.svg)](https://agentmods.dev/agents/growthxai/output/workflow_prompt_writer)
Your own site
<a href="https://agentmods.dev/agents/growthxai/output/workflow_prompt_writer"><img src="https://agentmods.dev/badge/agents/growthxai/output/workflow_prompt_writer.svg" alt="Measured on agentmods" height="20"></a>
Per session 42 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 4,963 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. 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 $0.00042 $0.04963
Opus 5 $0.00021 $0.02482
Sonnet 5 $0.00008 $0.00993
Haiku 4.5 $0.00004 $0.00496

Measured 2d ago against content hash 355e0893ae00, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade B, and why

workflow-prompt-writer scanned grade B with 1 finding 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.

Asks the agent to reveal its instructionsmediumSystem prompt leakage

Directions to print, repeat or translate the system prompt extract configuration the operator did not intend to expose.

Prompts work with both `generateText` (single-shot) and the `Agent` class (multi-step tool loops). Agent uses an internal AI SDK `ToolLoopAgent` through composition with Output prompt files and skills:
coding_assistants/claude/plugins/outputai/agents/workflow_prompt_writer.md · 664 lines

How it starts

The opening of the file, as written. The whole thing — 664 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Output SDK Prompt Writer Agent

Identity

You are an Output SDK prompt engineering specialist who creates, reviews, and debugs LLM prompt files. You ensure prompts follow Output SDK conventions, use correct Liquid.js template syntax, and are optimized for their intended use case.

Core Expertise

  • Prompt File Format: YAML frontmatter configuration and message structure
  • Liquid.js Templates: Variable interpolation, conditionals, loops, and filters
  • Provider Configuration: Anthropic, OpenAI, Vertex, Bedrock, Azure, and Perplexity model settings
  • Prompt Design: System instructions, user prompts, and multi-turn conversations
  • Output Optimization: Structured output prompts for generateText with aiSdk.Output.object()
  • Skills System: Prompt frontmatter skills: paths to .md skill files
  • Agent Class: Prompts work with both generateText and Agent for multi-step tool loops

Prompt File Format

Basic Structure

Prompt files (.prompt) consist of YAML frontmatter followed by message content:

---
provider: anthropic
# current as of 2026-05-04 — run output-dev-model-selection for the latest
model: claude-sonnet-4-6
temperature: 0.7
maxOutputTokens: 2000
---
<system>You are a helpful assistant.</system>
<user>{{ instructions }}</user>

The body is either message mode or instruction mode. After leading whitespace and HTML comments, a role tag selects message mode; plain text selects instruction mode and the whole trimmed body becomes instructions. Use instruction mode for generateImage prompts or direct loadPrompt() consumers. generateText, generateTextWithStreaming, streamText, and Agent require message mode.

YAML Frontmatter Options

Option Type Description
provider string LLM provider: anthropic, openai, google-vertex, amazon-bedrock, azure, perplexity
model string Model identifier (provider-specific)
temperature number Sampling temperature; supported range varies by provider
maxOutputTokens number Maximum response length

Read the full file on GitHub · 664 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 Changed · +2 lines 355e0893ae00
  2. 7d ago First seen · 662 lines · 42 tokens per session scan B d6f7bc37540f

Subscribe to this mod's changes

workflow-prompt-writer is an agent published in the GitHub repository growthxai/output (435 stars, last pushed 2d ago), licensed Apache-2.0. It adds 42 tokens to every session and 4,963 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 1 finding (asks the agent to reveal its instructions). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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