can1357/oh-my-pi · error · ValidationError

anthropic-messages: ${data.summary}

Error message

anthropic-messages: ${data.summary}

What it means

The anthropic-messages server endpoint validates incoming request bodies with an ArkType schema (anthropicMessagesRequestSchema). If the body fails validation, parseRequest throws a ValidationError whose message embeds ArkType's data.summary — a structured description of exactly which fields were wrong. This is a 4xx-class contract failure: the client sent a request that does not match the Anthropic Messages API shape this server accepts.

Source

Thrown at packages/ai/src/providers/anthropic-messages-server.ts:329

}

/**
 * Inbound `output_config.effort` wire literal → catalog `Effort` (1:1).
 * Values outside this table (none exist in the schema today) are ignored
 * rather than guessed at.
 */
const REASONING_EFFORT_BY_WIRE: Partial<Record<string, Effort>> = {
	low: Effort.Low,
	medium: Effort.Medium,
	high: Effort.High,
	xhigh: Effort.XHigh,
	max: Effort.Max,
};

export function parseRequest(body: unknown, headers?: Headers): ParsedRequest {
	const data = anthropicMessagesRequestSchema(body);
	if (data instanceof type.errors) {
		throw new AIError.ValidationError(`anthropic-messages: ${data.summary}`);
	}

	const now = Date.now();
	const messages: Message[] = [];
	for (const message of data.messages as AnthropicMessage[]) {
		if (message.role === "user") {
			for (const m of walkUserContent(message.content, now)) messages.push(m);
		} else {
			const assistant: AssistantMessage = {
				role: "assistant",
				content: walkAssistantContent(message.content),
				api: "anthropic-messages",
				provider: "anthropic",
				model: data.model,
				usage: emptyUsage(),
				stopReason: "stop",
				timestamp: now,
			};

View on GitHub (pinned to 9690622007)

Solutions

1. Read data.summary in the thrown ValidationError — it enumerates each field that failed and why; fix those fields
2. Validate the request body against the Anthropic Messages API schema before sending (use the official SDK's types or zod/arktype)
3. Pin/upgrade the client SDK version so its request shape matches what this server expects
4. Log the raw request body on failure to spot rewrites by intermediate proxies or serialization bugs (strings where numbers are expected)

Example fix

// before: unvalidated hand-rolled body
await fetch(endpoint, { method: "POST", body: JSON.stringify({ messages, model }) });
// after: required fields enforced up front
const body = { model, max_tokens: 1024, messages };
const parsed = anthropicMessagesRequestSchema(body);
if (parsed instanceof type.errors) throw new Error(parsed.summary);
await fetch(endpoint, { method: "POST", body: JSON.stringify(body) });

import { type } from "arktype";
// reuse the server's schema client-side before sending
const parsed = anthropicMessagesRequestSchema(body);
if (parsed instanceof type.errors) {
  throw new Error(`Invalid anthropic-messages request: ${parsed.summary}`);
}

function isArkTypeError<T>(v: unknown | T, err: unknown): err is type.errors {
  return err instanceof type.errors;
}

try {
  const res = await fetch(endpoint, { method: "POST", body: JSON.stringify(body) });
} catch (err) {
  if (err instanceof AIError.ValidationError && err.message.startsWith("anthropic-messages:")) {
    // message body embeds arktype summary listing each offending field
    logger.error("request rejected by anthropic-messages server", { detail: err.message });
  }
  throw err;
}

When it happens

Trigger: POSTing a body to the anthropic-messages endpoint with missing/ill-typed required fields (messages, model, max_tokens), wrong enum values for roles or stop sequences, or headers that fail optional header validation.

Common situations: Pointing an Anthropic SDK at this server with a version whose request shape diverges; hand-rolled HTTP clients omitting max_tokens or sending model as null; proxies rewriting the body; sending JSON with wrong types (max_tokens as string).

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• anthropic-messages: upstream ${message.stopReason}
• Anthropic cache refresh response omitted usage
• Anthropic thinking budget requires max_tokens greater than $
• Schema contains a circular object graph — cannot enforce str
• Schema node has no type, combinator, or $ref — cannot enforc

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/79ba8160aa66129c. Report an issue: GitHub.