Enforcing Structural Rigor in Claude
Production applications frequently require Claude to parse messy inputs and return strictly validated data formats. Claude is pretrained with an acute awareness of XML structural tags, making them the gold standard for prompt hygiene.
XML Prompting Hygiene
Wrapping prompt components in descriptive XML tags prevents boundary confusion and provides strong defenses against indirect prompt injection:
<context>
The candidate has 8 years of distributed systems experience in Go and TypeScript.<instructions> Extract all validated technical skills and format them according to the schema. Only include skills explicitly evidenced in the context. </instructions>
<format_requirements> Output strictly valid JSON matching the SkillExtraction interface. Do not enclose the response in backticks or preamble. </format_requirements> ```
Ensuring Preamble-Free JSON
To eliminate conversational filler ("Here is the JSON you requested:"), combine: 1. System instructions demanding raw JSON only. 2. Tool Use / Function Calling constrained with `tool_choice: { type: "tool", name: "submit_result" }`, forcing the model to speak purely via validated schema parameters.