402 Payment Required despite available token balance

**Description**

Requests to the Reader API are returning `402 Payment Required`, even though the account/API key shows an available token balance in the dashboard. This happens both with my original key and with a newly generated key (created via a private/incognito browser session), which suggests the issue is not tied to a specific key but possibly to something on the account or billing side.

**Steps to reproduce**

1. Generate or use an existing Jina API key with available token balance.
2. Send a request to the Reader endpoint (`read_url`) via the MCP server (`https://mcp.jina.ai/v1`), using the key in the `Authorization: Bearer ` header.
3. Observe the response.

**Expected behavior**

The request should succeed and return the extracted content, since the account has available tokens.

**Actual behavior**

The API returns `HTTP 402 Payment Required`.

**Environment**

- Endpoint: Reader (`read_url`) via MCP server, `https://mcp.jina.ai/v1`
- API key: ends in `...95Q10`
- Token balance: available (not zero) per dashboard
- Tested with two different keys (original + newly generated), same result on both

**Additional notes**

I found other reports of the same `402` error occurring despite available/topped-up balances in this repo's issue history, so this may not be an isolated case. Any guidance on what's causing this would be appreciated.

Start by reproducing the `read_url` request through `https://mcp.jina.ai/v1` with the documented Bearer key and confirm the dashboard balance and HTTP 402 response. Review the related 402 reports in the repository issue history and trace the Reader API billing or account-handling entry point. Done means requests from accounts with available tokens return extracted content, or the cause and required account state are documented.

Written by the indexing model from the issue text.