This prompt is designed for e-commerce and product operations teams that need to generate structured, consistent product catalog entries from unstructured or semi-structured source data. It binds each output field to a precise description, example, and constraint so the model produces records that downstream parsers, databases, and storefronts can consume without manual cleanup. Use this prompt when you are ingesting supplier spreadsheets, migrating legacy catalogs, or normalizing product data from multiple sources into a single schema. The ideal user is an engineer or product data manager who controls the target schema and needs the model to act as a disciplined data formatter, not a creative copywriter.
Prompt
Field Description Prompt for Product Catalogs

When to Use This Prompt
Defines the ideal job-to-be-done, user, and context for the Field Description Prompt for Product Catalogs, and clarifies when not to use it.
This is not a prompt for generating marketing copy or creative product descriptions. Its job is structural consistency and field-level discipline. Do not use it when the goal is persuasive language, brand voice development, or open-ended product storytelling. It is also not a replacement for a data validation pipeline; the prompt enforces output structure, but you must still validate units of measure, variant relationships, and referential integrity in your application layer. The prompt works best when paired with a defined JSON Schema, a set of allowed enum values, and a small number of few-shot examples that demonstrate tricky cases like multi-variant products or region-specific compliance fields.
Before using this prompt, define your target schema precisely. For each field, you should know its type, whether it is required, what format constraints apply (e.g., ISO 8601 dates, uppercase country codes), and what constitutes a valid value. If you cannot define these constraints, the model will guess, and guessing produces drift. Start with a small batch of 20-50 products, run the output through a schema validator, and review field-level accuracy before scaling to thousands of records. The next section provides the copy-ready prompt template you can adapt to your schema.
Use Case Fit
Where the Field Description Prompt for Product Catalogs works well, where it breaks, and what you need in place before relying on it.
Good Fit: Structured Catalog Ingestion
Use when: You need to convert supplier spreadsheets, legacy product descriptions, or unstructured marketing copy into a consistent catalog schema with defined fields, units, and constraints. Guardrail: Provide a complete field map with examples and allowed values before generation. Validate output against the schema immediately.
Bad Fit: Creative Product Marketing
Avoid when: The goal is to generate persuasive, brand-differentiated marketing copy. This prompt enforces structural consistency, which will strip voice and creative variation. Guardrail: Route to a separate role-specific tone prompt for marketing outputs. Use this prompt only for the canonical record of truth.
Required Input: Canonical Field Definitions
What to watch: Without a precise field map including data types, units of measure, and example values, the model will invent conventions that drift across records. Guardrail: Maintain a single source-of-truth field definition document. Pass it as part of the system context for every generation request.
Operational Risk: Unit-of-Measure Drift
What to watch: The model may silently convert units (e.g., inches to centimeters) or mix measurement systems within a single catalog, breaking downstream filtering and comparison. Guardrail: Declare a canonical unit per field in the schema. Add a post-generation validation step that flags mixed-unit records for human review.
Operational Risk: Variant Explosion
What to watch: When generating product variants (size, color, material), the model may create combinatorial explosions or miss required variant dimensions. Guardrail: Define variant axes explicitly in the prompt. Cap the number of generated variants per product. Validate that every variant has a complete set of required attributes.
Operational Risk: Hallucinated Specifications
What to watch: For products with sparse source data, the model may fill gaps with plausible but incorrect specifications, especially for technical attributes like wattage, voltage, or material composition. Guardrail: Require a confidence flag per field. Route low-confidence fields to a human review queue. Never publish unverified technical specs to a live catalog.
Copy-Ready Prompt Template
A copy-ready system prompt that binds each catalog field to a precise description, example, and constraint so the model produces consistent, machine-readable product records.
The following prompt template is designed to be placed in the system instructions or developer message layer of your AI application. It forces the model to generate structured product catalog entries where every field is explicitly defined, constrained, and exemplified. This reduces downstream parsing errors, unit-of-measure inconsistencies, and creative reinterpretation of field semantics that commonly break catalog ingestion pipelines.
textYou are a product catalog data entry assistant. Your only job is to generate a structured product record from the provided source data. Follow every field description, constraint, and example exactly. Do not add fields, skip fields, or reinterpret field meanings. ## Output Schema Generate a single JSON object with the following fields. Return ONLY the JSON object, no surrounding text, no markdown fences. [OUTPUT_SCHEMA] ## Field Descriptions and Constraints For each field in the schema, adhere to these rules: [FIELD_DESCRIPTIONS] ## Source Data Use only the following source data to populate the fields. If a field's value is not present in the source data, use null. Do not infer, guess, or hallucinate missing values. [SOURCE_DATA] ## Critical Constraints 1. Unit of Measure: Every quantitative field must include its unit exactly as specified in the field description. If the source data uses a different unit, convert it to the required unit and note the conversion in the [CONVERSION_NOTES_FIELD] field. 2. Variant Handling: If the source data describes multiple variants of the same product, generate a separate record for each variant. Populate the [VARIANT_ATTRIBUTES_FIELD] field with the distinguishing attributes. 3. Null Handling: Use null for any field whose value cannot be determined from the source data. Never use placeholder strings like "N/A", "TBD", or empty strings. 4. Enum Adherence: For any field with a defined set of allowed values, select ONLY from that set. If the source data suggests a value outside the allowed set, set the field to null and add a note to the [FLAGGED_ISSUES_FIELD] field. 5. Confidence: If you are uncertain about the correct value for a field due to ambiguous or conflicting source data, set the field to null and document the ambiguity in the [FLAGGED_ISSUES_FIELD] field. ## Examples Here are examples of correct output records: [EXAMPLES]
To adapt this template, replace each square-bracket placeholder with your specific configuration. The [OUTPUT_SCHEMA] should be a JSON Schema-like definition of your product record structure. The [FIELD_DESCRIPTIONS] should be a detailed breakdown of each field including its data type, allowed values, unit requirements, and an example value. The [SOURCE_DATA] is the raw product information you want to structure. The [EXAMPLES] should include at least one correct record and one edge case showing null handling for missing data. The optional [CONVERSION_NOTES_FIELD], [VARIANT_ATTRIBUTES_FIELD], and [FLAGGED_ISSUES_FIELD] placeholders should be replaced with the actual field names you define in your schema for those purposes. Before deploying, run this prompt against a golden dataset of known product records and validate that the output JSON parses correctly, all required fields are present, enum values are respected, and unit conversions are accurate.
Prompt Variables
Required and optional inputs for the Field Description Prompt. Each variable must be populated before the prompt is assembled and sent. Missing or malformed inputs are the most common cause of output inconsistency in catalog generation pipelines.
| Placeholder | Purpose | Example | Validation Notes |
|---|---|---|---|
[PRODUCT_CATEGORY] | Defines the top-level product category to scope terminology, units, and attribute conventions | Footwear > Running Shoes | Must match an entry in the approved category taxonomy. Reject if category is not in the canonical list. |
[FIELD_NAME] | The exact field identifier as it appears in the target schema or database column | upper_material | Must be a valid identifier (snake_case, camelCase, or PascalCase). No spaces or special characters. Validate against the target schema field list. |
[FIELD_DATA_TYPE] | The expected data type for the field value | string | Must be one of: string, number, boolean, array, object, null. Reject unknown types. Used to constrain the description's type guidance. |
[FIELD_REQUIRED] | Whether the field is mandatory for a valid product record | Must be true or false. Controls whether the prompt instructs the model to flag missing values as errors. | |
[ALLOWED_VALUES] | A constrained list of acceptable values, if the field is enum-controlled | ["leather", "mesh", "synthetic", "knit"] | Must be a valid JSON array of strings or null. If provided, the prompt will enforce strict enum adherence. Validate array syntax before prompt assembly. |
[UNIT_OF_MEASURE] | The unit in which the field value is expressed, if applicable | millimeters | Must be a recognized unit from the catalog's unit registry or null. If provided, the prompt will instruct the model to include the unit in the description and flag unitless values. |
[VARIANT_AWARE] | Whether the field can differ across product variants (size, color, etc.) | Must be true or false. If true, the prompt instructs the model to describe variant-specific behavior and note when a value applies only to the base product. | |
[EXAMPLE_VALUE] | A realistic example value that demonstrates correct formatting and constraints | "Full-grain leather with mesh panels" | Must conform to the declared data type and allowed values. Used as a few-shot anchor in the prompt. Reject if example violates its own constraints. |
Implementation Harness Notes
How to wire the Field Description Prompt into a product catalog pipeline with validation, retries, and human review.
The Field Description Prompt is designed to be called once per product field that needs enrichment, not once per product. In a typical catalog pipeline, you iterate over a list of field names extracted from your schema or data dictionary, calling the prompt for each field that lacks a description, example, or constraint. This per-field isolation keeps the prompt focused, reduces output variance, and makes validation failures easier to attribute and repair. The prompt expects three inputs: the field name, the product category context, and any existing catalog conventions the model should follow.
Wire the prompt into an application function that accepts a field record and returns an enriched field record. Before calling the model, validate that the field name is non-empty and that the category context is present. After receiving the output, run a structured validation pass: confirm that the description is between 20 and 200 characters, that the example value matches the field's expected data type, and that the constraint list contains at least one actionable rule. If validation fails, retry once with the specific validation error appended to the [CONSTRAINTS] placeholder. For high-volume catalogs, batch fields by category and use a single model call with a structured output schema to reduce latency, but keep per-field validation granular.
For regulated product categories such as supplements, electronics with safety ratings, or products with legal labeling requirements, route outputs through a human review queue before they land in the catalog database. Log every prompt version, input hash, output, and validation result so that field descriptions are auditable back to the model and prompt that generated them. Avoid using this prompt for fields that require precise regulatory language—those should be authored by domain experts and treated as source-of-truth records, not AI-generated content.
Expected Output Contract
Field-level output contract for the Field Description Prompt for Product Catalogs. Each row defines a required or optional field in the structured product record, its expected type, whether it must appear, and a concrete validation rule that can be checked in application code or by an LLM judge.
| Field or Element | Type or Format | Required | Validation Rule |
|---|---|---|---|
product_id | string (alphanumeric, max 50 chars) | Must match regex ^[A-Z0-9_-]+$. Reject if empty or contains spaces. | |
field_name | string (snake_case) | Must be a single valid field identifier from the input schema list. Reject if invented or rephrased. | |
description | string (1-3 sentences) | Must be between 10 and 300 characters. Reject if it copies the field_name verbatim or is empty. | |
example_value | string or number matching field type | Must be parseable as the declared data_type. Reject if example is a placeholder like 'example' or 'TBD'. | |
data_type | enum: string, number, boolean, date, array, object | Must be exactly one of the allowed enum values. Reject any variation in casing or wording. | |
unit_of_measure | string or null | If provided, must match a known unit from the catalog's unit registry. If null, field is dimensionless. | |
constraints | array of constraint objects or empty array | Each constraint object must have 'type' and 'rule' keys. Reject if constraints contradict the data_type. | |
variant_behavior | enum: shared, variant_specific, conditional or null | If product has variants, this field must not be null. Reject if 'variant_specific' but no variant key is referenced. |
Common Failure Modes
Field description prompts for product catalogs fail in predictable ways. Here are the most common failure modes and how to guard against them before they reach production.
Unit-of-Measure Inconsistency
What to watch: The model mixes units within the same field (e.g., '10 oz' and '250 ml' in the same size column) or invents units not specified in the schema. This breaks downstream filtering, comparison, and display logic. Guardrail: Bind each numeric field to an explicit unit enum in the prompt. Add a post-generation validator that checks all values in a column share the same unit. Flag mixed-unit records for human review before ingestion.
Variant Field Collapse
What to watch: When a product has variants (size, color, material), the model merges variant-specific attributes into a single record instead of generating separate rows. This produces one ambiguous entry instead of distinct SKUs. Guardrail: Include explicit variant-separation instructions with an example showing how one base product becomes multiple output records. Validate that each output row has a unique variant key combination. Reject collapsed outputs and retry with stronger separation language.
Field Description Drift Over Batches
What to watch: The model starts conforming to the data it sees rather than the field descriptions you provided. After processing several products with short descriptions, it shortens all subsequent descriptions even when the schema requires longer ones. Guardrail: Place field descriptions in the system prompt layer, not in user messages. Run periodic eval checks on a holdout set of diverse products. If field compliance degrades, re-anchor by prepending the full field schema to each batch.
Constraint Over-Interpretation
What to watch: The model treats field constraints as creative suggestions rather than hard rules. A constraint like 'description must be 50-200 characters' produces outputs of 35 or 250 characters because the model prioritizes fluent prose over length limits. Guardrail: Use numeric constraints with explicit enforcement language ('exactly', 'no fewer than', 'no more than'). Add a post-generation length validator that rejects out-of-range outputs and triggers a retry with the constraint repeated in the retry prompt.
Missing-Value Hallucination
What to watch: When the source data lacks a required field (e.g., material composition), the model invents plausible values instead of leaving the field null or marking it as unknown. This introduces false data that looks correct. Guardrail: Explicitly instruct the model to output null or a designated [UNKNOWN_TOKEN] when source evidence is absent. Add a validator that flags any non-null value when the source field was empty. Require human review for all filled fields with no source grounding.
Cross-Field Contamination
What to watch: Content from one field bleeds into another. The model puts sizing information into the color field or merges the product title into the description field, producing records that fail field-level validation. Guardrail: Use field-level output constraints that define what each field must contain and must not contain. Add a cross-field contamination check that searches for known patterns from one field appearing in another (e.g., color names in the size field).
Evaluation Rubric
Use this rubric to test the quality of generated field descriptions before integrating them into a production catalog pipeline. Each criterion targets a specific failure mode common in structured product data generation.
| Criterion | Pass Standard | Failure Signal | Test Method |
|---|---|---|---|
Schema Compliance | Output is valid JSON matching the [OUTPUT_SCHEMA] exactly; no missing required fields, no extra fields. | JSON parse error, missing [FIELD_NAME] or [DESCRIPTION], or presence of unsolicited commentary outside the JSON object. | Automated JSON schema validator run against the raw model output. |
Unit of Measure Consistency | The [UNIT] value matches the [PRODUCT_CATEGORY] standard and is consistent across all variant descriptions. | Mixing 'kg' and 'lbs' for the same product line, or using 'ml' for a solid product. | Regex pattern match against an allowed-units list per category; spot-check 10% of outputs manually. |
Constraint Adherence | The [DESCRIPTION] strictly follows all rules in [CONSTRAINTS] (e.g., character limit, no markdown, no subjective adjectives). | Description exceeds [MAX_LENGTH], contains banned words like 'amazing', or uses markdown formatting. | Automated length check, banned-word list grep, and markdown syntax detection. |
Example Grounding | The [EXAMPLE_VALUE] provided is a plausible, realistic instance of the [FIELD_NAME] for the given [PRODUCT_CATEGORY]. | Example is generic ('Item 1'), nonsensical ('Color: 5 kg'), or copied verbatim from the prompt instruction. | Human review of 20 random examples; automated check for exact string match with the prompt's own examples. |
Variant Handling | For products with variants, each variant's [FIELD_NAME] is described distinctly without contradicting the parent product. | All variants have identical descriptions, or a variant description contradicts the parent's base specification. | Deduplication check on variant descriptions; automated contradiction detection using a pre-defined rules engine. |
Null Handling | If [FIELD_VALUE] is not applicable, the [DESCRIPTION] explicitly states 'Not applicable' or uses the specified [NULL_REPRESENTATION]. | Field is omitted, left as an empty string, or contains hallucinated data like 'N/A' when a specific null token is required. | Automated check for empty strings; regex validation against the allowed [NULL_REPRESENTATION] token. |
Role Consistency | The output tone and structure match the defined [ROLE] persona (e.g., 'Technical Catalog Editor') without drifting into a different voice. | Description uses marketing language ('Buy now!') when the role is technical, or vice-versa. | LLM-as-judge evaluation with a rubric comparing output to a reference set of role-consistent descriptions. |
Confidence Indication | If [CONFIDENCE] is requested, the output includes a score between 0.0 and 1.0 that correlates with the specificity of the source data. | Confidence is always 1.0, missing, or is 0.0 for a perfectly clear input. | Automated range check (0.0-1.0); statistical analysis to ensure variance across a test batch. |
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Give teams answers from docs, tickets, runbooks, and product data with sources and permissions.
Useful when people spend too long searching or get different answers from different systems.

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Use AI to route work, draft outputs, trigger actions, and keep approvals and logs in place.
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Adapt This Prompt
How to adapt
Start with the base field description prompt and a small set of 5-10 products. Remove strict schema validation and let the model generate descriptions in a simple key-value format. Use a lightweight eval that checks only whether each requested field appears in the output.
codeFor each product in [PRODUCT_LIST], generate a field description record with these fields: [FIELD_NAMES]. Return as JSON.
Watch for
- Missing unit-of-measure consistency across variants
- Hallucinated spec values when source data is thin
- Field descriptions that drift into marketing copy instead of structured catalog entries

About the author
Prasad Kumkar
CEO & MD, Inference Systems
Prasad Kumkar is the CEO & MD of Inference Systems and writes about AI systems architecture, LLM infrastructure, model serving, evaluation, and production deployment. Over 5+ years, he has worked across computer vision models, L5 autonomous vehicle systems, and LLM research, with a focus on taking complex AI ideas into real-world engineering systems.
His work and writing cover AI systems, large language models, AI agents, multimodal systems, autonomous systems, inference optimization, RAG, evaluation, and production AI engineering.
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