Trying to connect to Salesforce MCP

### MCP server URL

https://api.salesforce.com/platform/mcp/v1/platform/sobject-reads

### Where does the issue occur?

When auth finishes and redirects back to Claude.ai

### Transport used

streamable-http

### Client registration type

Static

### SSE only: Does your server return the expected status code for POST requests?

Not applicable (my server does not use SSE)

### When did you last reproduce this?

2026-06-30 3:00pm CST

### Browser and OS

June 30, 2026. Around 3:00PM CST

### Describe the issue

Attempting to connect a Salesforce hosted MCP server (sobject-reads) to Claude.ai using a Salesforce External Client App with static OAuth credentials. The OAuth consent screen completes successfully on the Salesforce side and the user clicks Allow, but the connection fails when the flow redirects back to Claude.ai with the error "Authorization with the MCP server failed."

Org type: Salesforce Developer Edition. Tried both the production endpoint (https://api.salesforce.com/platform/mcp/v1/platform/sobject-reads) and the sandbox endpoint (https://api.salesforce.com/platform/mcp/v1/sandbox/platform/sobject-reads). The sandbox endpoint routes to test.salesforce.com which rejects Developer Edition credentials, so the production endpoint appears to be the correct one for this org type but still fails at the Claude-side handshake.

External Client App configuration: Permitted Users set to All users can self-authorize, IP Relaxation set to Relax IP restrictions, OAuth scopes include mcp_api, refresh_token, and id.

Reference codes from failed attempts: ofid_f4c633f1263653de and ofid_022c7273e1c4e9da.

### Issue details

```shell
Use something like this:

---

The Salesforce OAuth consent screen displays correctly and the user completes authorization successfully. After clicking Allow, Salesforce redirects back to Claude.ai but the MCP session handshake fails immediately with "Authorization with the MCP server failed."

Attempted fixes with no change in outcome: added `id` scope to the Connected App, switched between production and sandbox server URLs, attempted connection from both the Claude desktop app and the browser (claude.ai). The failure is consistent across all attempts and always occurs at the redirect back to Claude.ai, never on the Salesforce side.

The Connected App settings are: Distribution State Local, all five OAuth flow types unchecked, Require secret for Web Server Flow on, Require secret for Refresh Token Flow on, Require PKCE on. These are Salesforce defaults for a new External Client App.

Suspected cause: Developer Edition orgs may not be supported by the production MCP endpoint, but the sandbox endpoint is also incompatible because Developer Edition orgs authenticate through `login.salesforce.com`, not `test.salesforce.com`. There may be no supported endpoint for Developer Edition orgs in the current beta.
```

### Expected behavior

After completing the Salesforce OAuth consent screen and clicking Allow, the connector should be added successfully and appear as Connected in Claude's Connectors list. Claude should then be able to call the six sobject-reads tools against the authenticated Salesforce Developer Edition org.

### Logs from your server

```shell

```

### Additional context

This is a personal developer setup to validate Salesforce's hosted MCP servers before rolling out to an enterprise org. The two reference codes from failed connection attempts are the primary diagnostic artifacts. Salesforce's MCP documentation does not clarify which endpoint or org type combination is supported for Developer Edition orgs, and the hosted MCP server feature is marked as Generally Available on the Salesforce side while the Claude custom connector feature is still in Beta. It is unclear whether the incompatibility is a known limitation of the Beta or a configuration issue.