rohitg00/ai-engineering-from-scratch · error · ValueError

missing required fields: {', '.join(missing)}

Error message

missing required fields: {', '.join(missing)}

What it means

Error "missing required fields: {', '.join(missing)}" thrown in rohitg00/ai-engineering-from-scratch.

Source

Thrown at certifications/claude/lessons/10-tool-use-and-agentic-loops/code/main.py:171

        maximum = _integer_bound(schema, "maxItems")
        if minimum is not None and len(value) < minimum:
            raise ValueError(f"invalid item count for {location}: below minItems {minimum}")
        if maximum is not None and len(value) > maximum:
            raise ValueError(f"invalid item count for {location}: above maxItems {maximum}")
        if "items" in schema:
            for index, item in enumerate(value):
                _validate_schema_value(item, schema["items"], f"{location}[{index}]")

    if isinstance(value, dict):
        properties = schema.get("properties", {})
        if not isinstance(properties, dict):
            raise ValueError(f"schema properties for {location} must be an object")
        required = schema.get("required", [])
        if not isinstance(required, list) or not all(isinstance(name, str) for name in required):
            raise ValueError(f"schema required for {location} must be a string list")
        missing = [name for name in required if name not in value]
        if missing:
            raise ValueError(f"missing required fields: {', '.join(missing)}")
        unexpected = set(value) - set(properties)
        if unexpected and schema.get("additionalProperties") is False:
            raise ValueError(f"unexpected fields: {', '.join(sorted(unexpected))}")
        for name, item in value.items():
            if name in properties:
                _validate_schema_value(item, properties[name], f"{location}.{name}")


@dataclass(frozen=True)
class Tool:
    name: str
    description: str
    input_schema: dict[str, Any]
    handler: Callable[[dict[str, Any]], Any]
    mutates: bool = False

    def validate(self, arguments: dict[str, Any]) -> None:
        if not isinstance(arguments, dict):

View on GitHub (pinned to 39ea8a1c6d)

When it happens

Trigger: Thrown at certifications/claude/lessons/10-tool-use-and-agentic-loops/code/main.py:171 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of rohitg00/ai-engineering-from-scratch@39ea8a1c6d (2026-08-26). Data as JSON: /api/errors/3a17ff0851ab81d2. Report an issue: GitHub.