Four Tier-1 MCP SDKs ship 2026-07-28 betas: which to use for Sume
Google says the TypeScript, Python, Go and C# MCP SDKs have betas for the new spec. Run Sume from a stable release, and test the beta separately.
Keep production Sume calls on a stable SDK release for now and try the 2026-07-28 beta in a separate branch. A Google Developers Blog post dated August 5, 2026 says all four Tier-1 SDKs, TypeScript, Python, Go and C#, offer beta releases that support the new specification. Sume's hosted MCP lists protocol versions 2025-03-26, 2025-06-18 and 2025-11-25, so a client that sends the newer revision's headers may be refused.
The risk is small and easy to check: one tools_list call tells you.
What changes on the wire
Per Google and the Agentic AI Foundation migration post.
| Change | Source says | Effect on a Sume connection |
|---|---|---|
| No initialize handshake | Requests carry context in a _meta object | A client built for it may skip a call Sume still accepts |
| Header metadata | Mcp-Protocol-Version, Mcp-Method, Mcp-Name | Sume rejects a Mcp-Protocol-Version outside its list with 400 |
| Discovery | server/discover on demand | Check Sume's response before relying on it |
| Tasks extension | Polling pattern for long operations | Sume uses job tools and jobs_wait instead |
| Deprecations | Roots, Sampling, Logging, DCR and HTTP+SSE proposed for removal after July 2027 | Sume is tools-only, Streamable HTTP, POST |
A safe rollout
First, record the exact SDK version you run today. Second, create a branch with the beta, point it at Sume with a read-only call, and compare the HTTP status and the tool list with the stable branch. Third, only if the call succeeds, run one paid call with dry_run=true and an idempotency_key to see admission and cost without submitting a job. Keep the stable branch deployable until the beta passes.
- Pin exact versions in your lockfile.
- Do not test a beta with a key that has a large wallet behind it; use a small account.
- Re-run the check after each beta bump.
Reading the beta label
A beta tag tells you the API may still change. Google's post says the four SDKs offer beta releases for the new spec; it does not promise they stay compatible with servers that list only older versions. That is the exact situation with Sume today. Treat a green result on the beta as information about that day's build, and record the SDK version next to it.
Also keep an eye on the deprecation list. The Agentic AI Foundation post proposes removing HTTP+SSE, Roots, Sampling, Logging and dynamic client registration after a window that closes July 28, 2027. Sume's hosted server is Streamable HTTP and tools only, so none of those removals touch the tool calls, though a client that relied on dynamic registration for sign-in should be reviewed.
What Sume does not do
The Sume docs describe the hosted URL and its auth, not a bundled MCP client library; you use the SDK of your language with that URL. Sume also does not state a date for the newer revision in the sources used here, so treat the version list as the current fact and recheck it when the health response changes.
Sources
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