## TL;DR

If your You.com API calls return 401, check the auth plumbing before anything else.

## Fix

1. If your You.com API calls return 401, check the auth plumbing before anything else.
   Expected: you can confirm this matches your situation.

## When to use

- You are dealing with this situation.
- The symptom matches: You.com search API uses X-API-Key header, not Bearer.

## When NOT to use

- Unrelated issues with a different cause.
- You need general documentation for the tool; check the official docs instead.

## Compatibility

Reported per the linked source.

## Variant phrasings

### You.com search API uses X-API-Key header, not Bearer

## Why it happens

Official docs (You.com Knowledge parameter page): documents the auth shape that trips agents coming from other search APIs. The web search endpoint is POST https://ydc-index.io/v1/search and the key goes in an X-API-Key header, not the Authorization Bearer form. Body is JSON with query, count, and optional params.

## Edge cases

- If your error message differs even slightly, this is probably a different issue; search the exact text.
- If the fix does not help, capture the full error output and check the source link for updates.