Claude Agent SDK
Same engine as Claude Code without the browser, so authorization is headers only in practice. Server status is observable per server, which is how you find out a token expired.
- Client type
- SDK
- Protocol revision
initializeera
Support
Claude Agent SDK
- stdio
- Yes
- Streamable HTTP
- Yes
- Legacy SSE
- Yes
- Revision
initializeera- OAuth flow
- No
- Registration
- No
- Metadata doc
- No
- Client ID
- No
- resource
- No
- iss
- No
- Headers
- Yes
- Protocol revision
- Not published. The SDK runs the same engine as Claude Code, on the
initializehandshake.
Caveats and sources
Each one names the column it qualifies and cites the page it comes from, which is often not the page in the row's primary source.
- Runs the OAuth flow
- Documented as absent: the SDK opens no browser and runs no interactive flow. When a server answers with an authorization challenge and no stored token exists, the run continues without that server's tools and the server reports status
needs-auth. You complete the flow yourself and pass the token inheaders, which is why every discovery and registration column on this row is a no rather than an unknown. Source
Primary source
This row was last verified July 31, 2026 against the 2026-07-28 revision.