JuliusBrussee/caveman · error · Error

caveman agent: Standard Schema emitted invalid input JSON Sc

Error message

caveman agent: Standard Schema emitted invalid input JSON Schema

What it means

After obtaining a converted or supplied JSON Schema for a Standard Schema tool input, tool() sanity-checks that it is a plain object (isRecord). If the converter or inputJSONSchema returned an array, string, null, or a primitive, the value cannot be a JSON Schema and the factory throws 'Standard Schema emitted invalid input JSON Schema'.

Source

Thrown at packages/agent/src/primitives.ts:167

    let converted = "inputJSONSchema" in options
      ? options.inputJSONSchema
      : undefined;
    if (converted === undefined && standard.jsonSchema !== undefined) {
      try {
        converted = standard.jsonSchema.input({ target: "draft-07" });
      } catch (error) {
        throw new Error("caveman agent: Standard Schema cannot emit draft-07 input JSON Schema", {
          cause: error,
        });
      }
    }
    if (converted === undefined) {
      throw new Error(
        "caveman agent: Standard Schema needs inputJSONSchema or Standard JSON Schema conversion",
      );
    }
    if (!isRecord(converted)) {
      throw new Error("caveman agent: Standard Schema emitted invalid input JSON Schema");
    }
    input = converted as TSchema;
  }
  const definition = {
    kind: "tool",
    name: options.name,
    description: options.description,
    input,
    effect: options.effect,
    result,
    ...(typeof options.result === "object" ? { artifact: options.result } : {}),
    ...(options.allowRepeat === undefined ? {} : { allowRepeat: options.allowRepeat }),
    timeoutMs,
    ...(options.runtime === undefined ? {} : { runtime: options.runtime }),
    async execute(value: unknown, signal?: AbortSignal) {
      if (standard === undefined) {
        return options.execute(value as never, signal);
      }

View on GitHub (pinned to 27d5a3981a)

Solutions

1. Unwrap envelope returns: inputJSONSchema: envelope.schema rather than envelope
2. Check with Array.isArray(x) || typeof x !== "object" || x === null before passing
3. Upgrade the schema library if a new version returns the bare object directly

Example fix

// before
inputJSONSchema: converter.output // { draft: "07", schema: {...} }

// after
inputJSONSchema: converter.output.schema // the bare object

const isRecord = (v: unknown): v is Record<string, unknown> =>
  typeof v === "object" && v !== null && !Array.isArray(v);
if (!isRecord(converted)) {
  throw new Error("JSON Schema converter must return a plain schema object");
}

const isJsonObject = (v: unknown): v is Record<string, unknown> =>
  typeof v === "object" && v !== null && !Array.isArray(v);

When it happens

Trigger: A schema library whose jsonSchema.input() returns a { $schema, schema } envelope instead of the bare schema object, or a caller passing inputJSONSchema: "string" / an array of schemas. Note: converters returning undefined take error 176's path instead.

Common situations: Mismatch between what a given validator's converter returns (some return { draft, schema } wrappers) and what this package expects (the schema object itself), or hand-written inputJSONSchema values built by JSON.parse of something that was not an object.

Related errors

• caveman agent: Standard Schema needs inputJSONSchema or Stan
• caveman agent: file path is required
• caveman agent: invalid tool name ${JSON.stringify(options.na
• caveman agent: unknown tool effect ${JSON.stringify(options.
• caveman agent: unknown tool result policy ${JSON.stringify(r

AI-assisted analysis of JuliusBrussee/caveman@27d5a3981a (2026-08-15). Data as JSON: /api/errors/da34033abdc67d10. Report an issue: GitHub.