earendil-works/pi · error

Grammar tool call "${toolName}" requires argument "${inputPr

Error message

Grammar tool call "${toolName}" requires argument "${inputProperty}" to be a string.

What it means

Error "Grammar tool call "${toolName}" requires argument "${inputProperty}" to be a string." thrown in earendil-works/pi.

Source

Thrown at packages/ai/src/api/constrained-sampling.ts:152

	format: "lark" | "regex";
	definition: string;
	inputProperty: string;
}

export interface GrammarToolInputJsonBuffer {
	input: string;
	started: boolean;
	closed: boolean;
}

export function getGrammarToolInput(
	toolName: string,
	arguments_: Record<string, unknown>,
	inputProperty: string,
): string {
	const input = arguments_[inputProperty];
	if (typeof input !== "string") {
		throw new Error(`Grammar tool call "${toolName}" requires argument "${inputProperty}" to be a string.`);
	}
	return input;
}

export function appendGrammarToolInputJsonDelta(
	buffer: GrammarToolInputJsonBuffer,
	inputProperty: string,
	nextInput: string,
	close: boolean,
): string | undefined {
	if (buffer.closed) {
		if (close && nextInput === buffer.input) return undefined;
		throw new Error(`grammar tool input for property "${inputProperty}" changed after it was closed`);
	}
	if (!nextInput.startsWith(buffer.input)) {
		throw new Error(`grammar tool input for property "${inputProperty}" changed non-monotonically`);
	}

View on GitHub (pinned to 4af9d21d3b)

Solutions

1. Declare the grammar tool argument property with type string.

When it happens

Trigger: Thrown at packages/ai/src/api/constrained-sampling.ts:152 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of earendil-works/pi@4af9d21d3b (2026-08-24). Data as JSON: /api/errors/73c6e85c06743282. Report an issue: GitHub.