Claude MCP connector: 2025-04-04 beta header is deprecated
Claude's connector page shows mcp-client-2025-11-20 and marks 2025-04-04 deprecated; the release notes name mcp-client-2026-09-15. State both.
Two Anthropic pages disagree on the current MCP connector beta header, and you should state both rather than pick one. The connector page, read on 2026-10-05, shows mcp-client-2025-11-20 and marks mcp-client-2025-04-04 as deprecated. The API release notes list mcp-client-2026-09-15 under the entry dated 2026-09-22. If your code still sends the 2025-04-04 header, it is on the deprecated one either way.
What the two pages say
| Header | Where it appears | Status |
|---|---|---|
mcp-client-2025-04-04 | Connector page | Deprecated |
mcp-client-2025-11-20 | Connector page | Shown as the header to use |
mcp-client-2026-09-15 | API release notes, 2026-09-22 entry | Introduced; the connector page did not show it when read |
What to do about the discrepancy
The two pages do not settle which header is right for a new integration, so do not guess. Practical steps: read the connector page the day you deploy, test with the header it shows, and then read the release notes for a newer entry. Treat the header as a pin you update on purpose, because the older header is already marked deprecated.
What Sume asks of you
Nothing on the header: Sume's hosted MCP at https://mcp.sume.com/mcp does not choose the Anthropic beta header. What matters on the Sume side is auth and tool scope. The connector page says it takes OAuth bearer tokens. Sume's OAuth gives mcp:read by default and mcp:write as a consent toggle, and an API key sees the full tool set. Paid tools still need an idempotency_key.
A read-only OAuth token will list read tools only. If you expect generate_video in the tool list and do not see it, check the grant before you check the header.
Checklist
- Search your code for
mcp-client-2025-04-04and replace it. - Pin the header in one constant, so a change is one edit.
- After any header change, call a read-only Sume tool such as
tools_listand compare the result. - Do not send API keys through chat; pass them as a bearer token from your server.
Timeline
The dates tell part of the story. The deprecated header carries 2025-04-04, the connector page's header carries 2025-11-20, and the release notes entry that names the third header is dated 2026-09-22. That is three header versions across about 17 months, from April 2025 to September 2026. Expect another. A constant in one place, and a smoke test that calls one read-only Sume tool, makes the next change a one-line edit.
Because the Anthropic pages disagree today, record the date you checked and which page you followed in your repository notes. Then the next engineer can tell whether a mismatch is a bug or a page that has moved.
Sources
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