Custom connector shows "Connected" with zero OAuth consent screen shown — reproduces across 2 of 3 accounts, same MCP server

### MCP server URL or name

https://mcp.freee.co.jp/mcp

### How are you connecting to this server?

From a custom connector URL I entered manually

### Where does the issue occur?

When pressing the Connect button

### When did you last reproduce this?

2026-07-14, morning JST

### Browser and OS

Chrome, Windows

### Describe the issue

Summary
When adding a custom connector for freee's official remote MCP server (https://mcp.freee.co.jp/mcp) in claude.ai, clicking "Connect" never shows the freee OAuth login/consent screen. The connector immediately shows "Connected" without any authentication step occurring. The connector's tool permissions screen correctly lists all 13 tools (7 read-only, 6 write/delete) as not disabled, but the tools are never callable in chat — tool_search returns zero results for any tool from this connector.

Reproduction across accounts
We tested this on 3 separate individual Claude Pro accounts (not Team/Enterprise), all following the identical procedure:
- Account A: OAuth consent screen appeared normally, login succeeded, connector works, freee_current_user and other tools callable normally.
- Account B: No consent screen shown. Connector immediately "Connected." Tools listed in settings but not callable in chat.
- Account C: Same as Account B.

Steps already ruled out
- Not a session/cache issue: reproduces in a fresh Incognito/Private window with no prior freee or Claude session
- Not browser-specific: reproduces identically in both claude.ai (browser) and the Claude Desktop app
- Not a freee-account issue: the affected users' freee accounts log in normally via freee's own web UI, with correct company/workspace access
- Not a plan-tier issue: all three Claude accounts are on the same individual Pro plan, so no admin-level connector policy should be in play
- Deleting and recreating the connector multiple times did not resolve it for the affected accounts
- Model (Sonnet 5 / Opus 4.8) does not affect the outcome

Related issues
This looks like the same class of bug as:
- #406 — "Custom connector marked 'connected' but Claude makes zero HTTP requests after first OAuth attempt fails"
- #476 — "Custom remote MCP connector: tools never surfaced to the model in claude.ai web, while the broker completes the full OAuth + MCP handshake server-side"

What we'd like to know
- Whether this is a known/tracked backend issue affecting a subset of accounts
- Whether there's a way to force a fresh OAuth handshake without deleting/recreating the connector
- Any workaround while we wait for a fix

### Error details

```shell
No pop-up error or error ID was shown in Claude.ai. The connector silently transitions to "Connected" status with no visible error at any point.
```

### Expected behavior

Clicking "Connect" should open freee's OAuth login/consent screen, allow the user to log in and authorize, and only then mark the connector as "Connected" with tools actually callable from chat.

### Additional context

What we'd like to know:
- Whether this is a known/tracked backend issue affecting a subset of accounts
- Whether there's a way to force a fresh OAuth handshake without deleting/recreating the connector
- Any workaround while we wait for a fix, beyond falling back to a local/stdio MCP setup

Happy to provide additional details (account IDs, timestamps of each attempt) via a private channel if needed.

Note: We reviewed #535, which shows a superficially similar symptom (Connected but tools missing from tool_search). However, in that case the root cause was eventually traced to a configuration issue on the reporter's own self-hosted server. In our case, we can rule out a server-side cause: the exact same MCP server URL (https://mcp.freee.co.jp/mcp, freee's official server) works correctly for one of our three accounts (Account A), while failing identically for the other two on the same day, using the same procedure. This points to per-account handling on the Claude/Anthropic side rather than a server-side issue.