[BUG] MCP client doesn't automatically handle `-32001` insufficient scope errors per specification

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Summary

According to the MCP specification for Runtime Insufficient Scope
Errors, when a tool
returns a -32001 error code indicating insufficient OAuth scope, the MCP client should automatically detect this and re-initiate the
authorization flow.

Claude Code currently does not handle this automatically, requiring users to manually reconnect via /mcp to grant additional
permissions.

## Current Behavior

When an MCP tool returns an insufficient scope error:
```json
{
"error": {
"code": -32001,
"message": "Insufficient scope: This tool requires additional permissions for account acct_xxx. Please reauthorize with <scope_name>
scope."
}
}

Claude Code displays the error but does not automatically trigger reauthorization. The assistant must either:

1. Manually call a reauthorization tool (if available)
2. Instruct the user to run /mcp to reconnect

What Should Happen?

Expected Behavior

Per the MCP spec, the client should:

1. Detect the -32001 error code
2. Automatically re-initiate the OAuth authorization flow
3. Prompt the user to grant the additional scopes
4. Retry the operation once reauthorization completes

• MCP server: OAuth-enabled MCP server

Error Messages/Logs

MCP Specification Reference

  https://modelcontextprotocol.io/specification/2025-11-25/basic/authorization#runtime-insufficient-scope-errors

Steps to Reproduce

Reproduction Steps

1. Connect to an MCP server with OAuth support
2. Authorize with limited scopes for a specific resource
3. Attempt to call a tool that requires additional permissions
4. Observe that a -32001 error is returned
5. Note that no automatic reauthorization flow is triggered

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.39 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_