{
  "practice": {
    "id": "prc_required_vs_optional",
    "title": "Be explicit about which parameters are required vs. optional, and what defaults apply",
    "category": "clarity",
    "description": "If a parameter is optional, the description (or schema) should say so and state what happens when it is omitted -- silently assumed defaults are a common source of wrong tool calls.",
    "example_good": "\"unit (optional): \"\"celsius\"\" or \"\"fahrenheit\"\". If omitted, defaults to the location's local convention.\"",
    "example_bad": "An optional parameter with no default behavior documented anywhere.",
    "source_note": "General JSON Schema / function-calling best practice.",
    "created_at": "2026-07-02 08:28:30",
    "cite_as": "https://subagentdescriptions.com/api/practices/prc_required_vs_optional"
  }
}