Remote MCP OAuth: prompt=consent hardcoded on every authorize request breaks Entra tenants with user-consent disabled

Summary

Claude Code 2.1.109's remote HTTP MCP transport hardcodes prompt=consent on every OAuth authorize request. This forces Microsoft Entra ID to show the consent UI on every sign-in, regardless of whether admin consent has already been granted tenant-wide.

In Entra tenants where user consent is disabled (a common enterprise policy), non-admin users are routed into the admin consent request workflow ("This app requires your admin's approval" + "Enter justification") on every connection attempt — even after an admin has explicitly granted tenant-wide consent on the app registration. There is no "Accept" button; the user is blocked.

Reproduction

1. Set up a .NET MCP server with Entra JWT Bearer auth + ModelContextProtocol.AspNetCore MCP authentication scheme (RFC 9728 protected resource metadata)
2. Create a public client Entra app registration with PKCE, access_as_user scope, admin consent granted tenant-wide
3. Ensure the Entra tenant has Enterprise applications → Consent and permissions → User consent settings set to "Do not allow user consent" (common in enterprise/MSP tenants)
4. Add the MCP server to Claude Code:

``bash
claude mcp add --transport http --client-id <app-reg-id> --callback-port 6274 my-server https://my-server.example.com/mcp
``

1. /mcp → Authenticate

Expected: Since admin consent is already granted, Entra should skip the consent prompt and issue tokens directly.

Actual: The authorize URL contains &prompt=consent, which forces Entra to show the consent UI. With user consent disabled at the tenant level, Entra shows the admin-approval-required form instead of an Accept button. Non-admin users are blocked indefinitely.

The authorize URL Claude generates

https://login.microsoftonline.com/{tenant}/oauth2/v2.0/authorize
  ?response_type=code
  &client_id=<app-reg-id>
  &code_challenge=<pkce>
  &code_challenge_method=S256
  &redirect_uri=http://localhost:6274/callback
  &scope=https://my-server.example.com/mcp/access_as_user+offline_access
  &prompt=consent          ← this is the problem
  &resource=https://my-server.example.com/mcp

Impact

Any Entra tenant with user consent disabled (standard enterprise security posture) cannot use Claude Code's remote MCP transport without one of these workarounds:

1. Change the tenant's consent policy — flip to "Allow user consent for apps". Works but requires a Global Admin to weaken the tenant-wide policy for all apps, not just this one.
2. Manually edit the auth URL — strip &prompt=consent from the URL Claude opens in the browser, then paste the modified URL. Per-sign-in manual step; not scalable.
3. Sign in as a Global Admin — admins see a "Consent on behalf of organization" checkbox. Works for the admin themselves but not for regular users.

Suggested fix

Either:

• A) Don't send prompt=consent at all — let Entra decide whether to show the prompt based on the existing consent state. If consent hasn't been granted yet, Entra will prompt automatically on first sign-in.
• B) Send prompt=consent only on the first sign-in for a given server (when no cached tokens exist), not on reconnections or token refreshes.
• C) Make prompt=consent configurable — e.g. a --no-prompt-consent flag on claude mcp add, or an MCP server config option.

Option A is the simplest and matches the behavior of other OAuth clients (Azure CLI, VS Code, etc.) that work fine with Entra tenants that have user consent disabled.

Environment

• Claude Code: v2.1.109
• OS: Ubuntu 22.04 (WSL2)
• Identity provider: Microsoft Entra ID (Azure AD), single-tenant
• MCP SDK: ModelContextProtocol.AspNetCore 1.2.0
• Server: ASP.NET Core .NET 10

References

• Microsoft docs on prompt=consent: https://learn.microsoft.com/en-us/entra/identity-platform/v2-oauth2-auth-code-flow#request-an-authorization-code