What
Apps that connect to a Claude Code session can now find out which version of Claude Code is running it.
- The session info that client apps can request gains an optional
claude_code_versionfield. It holds the version of the process that runs the session's turns, the same value the session reports when it starts (system/init). Older versions of Claude Code leave it out. - The
initializereply sent to a connecting program now includesclaudeCodeVersion, set to the build's version. - Remote Control, which lets you drive a session from another device, now includes
claude_code_versionin its initialize reply when one is available.
Separately, results from SDK-provided MCP tools can now include tool_reference blocks that name a tool, in some cases. Before, only text, image and document blocks were accepted.
Why
A client app attached to a session, including through Remote Control, can tell which Claude Code version it is talking to. Because older versions leave the field out, clients should handle it being missing.
Names in the bundleclaude_code_version
Documented inclaude-code/agent-sdk/typescript
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Confirmed since
Anthropic's documentation has since written up claude_code_version, on Agent SDK reference - TypeScript.
claude_code_version?: string;agent-sdk/typescript see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up claude_code_version, on Agent SDK reference - TypeScript.