Engineering

XML Output Prompts

Legacy integrations and enterprise systems still speak XML. The output contract for well-formed, single-root XML responses — same engine, XML rules.

Overview

XML output is a compatibility play: SOAP-era integrations, enterprise middleware, feed formats. The contract engine is the same as JSON's — schema, example, validation, strictness — with XML's failure modes addressed by name: exactly one root element, one child element per field, entity escaping for &, <, and >. This resource loads an invoice-metadata contract in XML mode. One boundary worth knowing: this is XML as OUTPUT — using XML tags to structure your prompt's INPUT for Claude is a different technique, covered by the System Prompt Generator.

Workflow

Generate in XML mode
Note the single-root rule and the escaping rule — XML's two signature failures, addressed by name.
Check the empty-element convention
Unknown optional values become empty elements, keeping the element set stable for downstream XPath.
Keep element order
Strict mode pins schema order — XML consumers are far more order-sensitive than JSON ones.

Why This Works

Naming XML's failure modes (multiple roots, unescaped entities) prevents them specifically
A stable element set with empty-element nulls keeps XPath expressions valid across runs
The output/input boundary keeps this tool out of Claude-tag territory — different problem, different tool

Best for

Legacy system integrations where XML is non-negotiable
Middleware pipelines validating against XML structure
Enterprise environments mid-migration from XML to JSON

Not for

Structuring prompt INPUT with XML tags for Claude — that's input formatting, see the System Prompt Generator
Greenfield integrations — JSON parses cheaper; use the format select

Use cases

Feeding model output into SOAP-era and enterprise XML consumers
Generating feed-format entries that downstream XML parsers ingest
Porting an existing JSON contract to an XML-only integration

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

TASK
Read the invoice in the input and return its metadata as a structured record for our accounting system.

OUTPUT FORMAT
Return your entire response as a single well-formed XML document with <result> as the root element, matching the schema below.

SCHEMA
Each field, its type, and its meaning:
- invoice_number (string, required): Invoice reference number
- issue_date (string, required): Issue date, YYYY-MM-DD
- vendor (string, required): Issuing company name
- total (number, required): Grand total as a decimal number
- currency (string, required): ISO currency code
- line_item_count (number, optional): Number of line items

EXAMPLE OF A VALID RESPONSE
<result>
  <invoice_number>REC-1042</invoice_number>
  <issue_date>2026-06-10</issue_date>
  <vendor>Acme Corp</vendor>
  <total>49.99</total>
  <currency>USD</currency>
  <line_item_count>3</line_item_count>
</result>

VALIDATION RULES
- Every required field must be present.
- Optional fields with no value: include the element, leave it empty.
- Field types must match the schema: numbers without quotes, booleans as true/false.

OUTPUT RULES
- Return only the XML document — no text before or after it.
- Do not wrap the XML in markdown code fences.
- Use exactly one <result> root element; one child element per field.
- Escape &, <, and > inside element values; use empty elements for unknown values.

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