Base request
The 301-token request remaining after tools and skill-description text are removed: system blocks, messages, skill-listing structure, and request controls.
- Message Context: Current date reminder
Text content block sent as messages[0].content[0] with role user.
Type: Message context - Message Context: User prompt
Text content block sent as messages[0].content[1] with role user.
Type: Message context - Request Controls
Non-text request controls sent by default in the SDK query request.
Type: Request controls - Skill Listing System Message
System-role message listing SDK-shipped/runtime skills available to the Skill tool.
Type: Skill listing - System Block: SDK identity
SDK identity system text sent by default.
Type: System block - System Block: Version metadata
Internal Claude Code/SDK version and entrypoint metadata.
Type: System block