Broker-Side Bug for NetSuite MCP Connector for Sandbox Instance Only

### MCP server URL or name

https://3658677-sb1.suitetalk.api.netsuite.com/services/mcp/v1/suiteapp/com.netsuite.mcpstandardtools

### How are you connecting to this server?

From browsing the MCP server directory

### Where does the issue occur?

When auth finishes and redirects back to Claude.ai

### When did you last reproduce this?

2026-07-30 01:45 PM Eastern

### Browser and OS

Chrome 150.0.7871.129 on Mac OS 15.7.4

### Describe the issue

Attempting to use the NetSuite Connector to connect Claude to my NetSuite Sandbox instance. After going through the connect steps, receiving a version of this error message every time, just the ofid value changes: Your account was authorized, but NetSuite returned an error when connecting. You can try again, or check that the server is working. If this persists, share this reference with support:
"ofid _16acdd2fc206c2ee"

I am able to successfully connect Claude to my NetSuite Production instance with no issues. I am trying to connect to my NetSuite Sandbox instance using the same role with same permissions that is not an Administrator role, verified the MCP SuiteApp/bundle installed matches between Production and Sandbox, and the integration is installed and enabled. The execution log in Sandbox is completely empty, despite the numerous attempts by both myself and others to connect.

Per Claude.ai, the important detail: the error message changed, but the actual evidence didn't — NetSuite still received nothing. So despite the more specific-sounding wording this time ("NetSuite returned an error when connecting"), the empty log tells us the same thing as before: the request never left Claude's broker to reach your Sandbox endpoint. The new phrasing is likely just a different error path in the broker's own code, not a sign that NetSuite is now involved in rejecting the request.

So this is still consistent with a broker-side failure, not a NetSuite-side one — you can treat it as the same underlying issue, just surfacing with different (and slightly misleading) text.

I'd fold this into the same report to Anthropic rather than treating it as a new bug:

ofid_16acdd2fc206c2ee (this latest attempt)
ofid_b8c358878f6b4dbb (the earlier attempt)
Both show empty Sandbox Execution Log at time of failure
Error message text is inconsistent between attempts despite identical underlying symptom (no request ever reaches NetSuite) — worth mentioning, since that inconsistency itself might help their engineers narrow down which code path in the broker is failing
Production continues to connect successfully throughout, same account, same role pattern

That inconsistency in error text for the same root failure is actually a useful data point for whoever's debugging this on Anthropic's side, so I'd include both ofids and both exact error strings verbatim in whatever you send to support or file on the GitHub tracker. Beyond that, I don't think there's more to diagnose from your end — you've isolated this about as cleanly as possible.

### Error details

```shell
Your account was authorized, but NetSuite returned an error when connecting. You can try again, or check that the server is working. If this persists, share this reference with support:
"ofid _16acdd2fc206c2ee"
```

### Expected behavior

My NetSuite Sandbox instance to successfully connect to Claude like my NetSuite Production instance was able to do successfully.

### Additional context

Link to issues #258 and #300 as prior reports of the same pattern, since yours is a new instance of it (just prod/sandbox reversed from #300's case)