JuliusBrussee/caveman · error · Error

caveman agent: Standard Schema cannot emit draft-07 input JS

Error message

caveman agent: Standard Schema cannot emit draft-07 input JSON Schema

What it means

When a tool's input is a Standard Schema (the vendor-neutral interface exposing a '~standard' property), tool() tries to obtain a draft-07 JSON Schema by calling standard.jsonSchema.input({ target: "draft-07" }) — the wire format models require. If the schema library's converter throws during that conversion, the error is wrapped as 'Standard Schema cannot emit draft-07 input JSON Schema' with the original error attached as cause.

Source

Thrown at packages/agent/src/primitives.ts:156

    throw new Error(`caveman agent: unknown tool result policy ${JSON.stringify(result)}`);
  }
  const timeoutMs = options.timeoutMs ?? 30_000;
  if (!Number.isSafeInteger(timeoutMs) || timeoutMs <= 0) {
    throw new Error("caveman agent: tool timeoutMs must be a positive integer");
  }
  const standard = standardToolSchema(options.input);
  let input: TSchema;
  if (standard === undefined) {
    input = options.input as TSchema;
  } else {
    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,

View on GitHub (pinned to 27d5a3981a)

Solutions

1. Inspect error.cause to see which schema construct failed to convert
2. Remove or replace draft-07-incompatible keywords from the input schema
3. Supply the JSON Schema directly via options.inputJSONSchema, bypassing conversion
4. Downgrade/switch the schema library to a version whose converter targets draft-07

Example fix

// before
const t = tool({
  name: "search",
  effect: "read",
  input: mySchema, // mySchema uses prefixItems (draft 2020-12 only)
  execute: ...,
});

// after
const t = tool({
  name: "search",
  effect: "read",
  input: mySchema,
  inputJSONSchema: {
    type: "object",
    properties: { query: { type: "string" } },
    required: ["query"],
  },
  execute: ...,
});

let draft07: unknown;
try {
  draft07 = schema["~standard"].jsonSchema?.input({ target: "draft-07" });
} catch {
  draft07 = undefined;
}
if (draft07 === undefined) {
  // supply inputJSONSchema explicitly instead of letting tool() convert
}

try {
  tool({ name, effect: "read", input: schema, execute });
} catch (e) {
  if (e instanceof Error && e.message.includes("draft-07")) {
    // inspect e.cause for the failing keyword; strip it or pass inputJSONSchema
  }
  throw e;
}

When it happens

Trigger: Using a Standard Schema validator whose jsonSchema converter cannot serialize some construct to draft-07 (e.g. draft-2020-only keywords, exotic formats, or symbols in the schema). The underlying converter error is in error.cause.

Common situations: Newer schema libraries defaulting to draft 2020-12, schemas using keywords with no draft-07 equivalent (e.g. prefixItems, some unevaluated* forms), or version drift between the schema library and this package's expectations.

Related errors

• caveman agent: Standard Schema needs inputJSONSchema or Stan
• caveman agent: Standard Schema emitted invalid input JSON Sc
• caveman agent: tool Standard Schema must implement version 1
• caveman agent: tool Standard JSON Schema converter is invali
• ${path} hooks must be a JSON object; refusing to overwrite i

AI-assisted analysis of JuliusBrussee/caveman@27d5a3981a (2026-08-15). Data as JSON: /api/errors/cd336f15c27c3e8f. Report an issue: GitHub.