Engineering

YAML Output Prompts

When the consumer is a config file or a human-reviewed pipeline, YAML beats JSON. The same output-contract engine, rendered as a YAML mode.

Open in JSON Output Prompt Builder

Overview

YAML output makes sense in a narrow band: configuration files, CI pipelines, and outputs a human reviews before committing. The contract mechanics are identical to JSON — schema, example, validation, strictness — with YAML-specific rules taking over: two-space indentation, quoting for special characters, no document separators. This resource loads an event-registration contract in YAML mode to show the engine's format switch in action; if your consumer is code rather than a file, the same schema is one click away from JSON.

How to use this resource

Generate in YAML mode

Same schema engine, YAML serializer — note the format-specific rule block.
Check the indentation rule

Two-space indentation is pinned explicitly; indentation drift is YAML's signature failure.
Flip formats to compare

Switch the select to JSON and watch the contract re-render — the schema investment is format-portable.

Why This Works

Format-specific rules address each format's own failure modes — YAML's is indentation, not fences
One engine across formats means the schema is defined once and rendered anywhere
Choosing the format by consumer (file vs parser) is the decision the mode select encodes

Best for

DevOps and CI workflows where YAML is the native tongue
Outputs destined for files rather than parsers
Teams that already settled the JSON-vs-YAML question per consumer

Not for

Code consumers — JSON parses more predictably; switch the format select back
Deeply nested structures where YAML indentation errors get expensive

Use cases

Generating config-file entries a human reviews before commit
Producing pipeline definitions in YAML-native ecosystems
Switching an existing JSON contract to YAML without redesigning it

FAQ

When should I use YAML output instead of the JSON output prompt for AI-generated structured data?

Choose YAML mode when the consumer is a config file, a CI pipeline, or output a human reviews before committing; keep JSON when code parses it. The schema is identical across both, so flipping the format select re-renders the same event-registration contract in the other syntax. For deeply nested structures, JSON parses more predictably.

Why does the AI wrap my YAML in ```yaml code fences and how do I stop it?

The generated prompt carries an OUTPUT RULE that says return only the YAML document and do not wrap it in markdown code fences, precisely because assistants default to fencing YAML. If fences still appear, strip them before your parser reads the file, or re-run the prompt keeping that rule intact. NewPrompt does not run the model or clean the output for you.

Does the YAML output prompt guarantee my config file is valid before I commit it?

It does not guarantee validity; the prompt pins two-space indentation and null-for-unknown rules to reduce YAML's signature failure, but you run it in your own assistant and own the review. That is why this contract targets human-reviewed configs: check indentation and that dietary_notes is set to null rather than omitted before you commit.

Customize This Resource

Opens this setup in JSON Output Prompt Builder. Generate to get the full output contract — then adjust the schema, format, and strictness.

Open in JSON Output Prompt Builder

Prompt Template

Copy it as-is, or use Open in JSON Output Prompt Builder to load it pre-filled and customize it with your own context.

TASK
Turn the registration request in the input into a structured event registration entry.

OUTPUT FORMAT
Return your entire response as a single valid YAML document matching the schema below.

SCHEMA
Each field, its type, and its meaning:
- attendee_name (string, required): Attendee's full name
- email (string, required): Contact email
- event_name (string, required): Event being registered for
- ticket_type (string, required): standard, vip, or student
- dietary_notes (string, optional): Dietary requirements or null

EXAMPLE OF A VALID RESPONSE
attendee_name: Jane Smith
email: user@example.com
event_name: Annual Customer Summit
ticket_type: standard
dietary_notes: Short free-text description

VALIDATION RULES
- Every required field must be present.
- Optional fields with no value: set them to null — do not omit the key.
- Field types must match the schema: numbers without quotes, booleans as true/false.

OUTPUT RULES
- Return only the YAML document — no text before or after it.
- Do not wrap the YAML in markdown code fences.
- Use two-space indentation; include every required field and use null for unknown values.
- Quote string values that contain special characters.

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Related tools

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JSON Output Prompt Builder

Build prompts that return structured data — JSON first, with YAML, XML, and CSV modes — parseable every time.

Structured Output

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