/v1/messages endpoint is a native passthrough for Anthropic
upstreams. The body forwards verbatim — cache_control: ephemeral markers,
image content blocks, and thinking blocks all preserved.
Python
Node
Prompt cache (the headline feature)
cache_control markers are forwarded to Anthropic verbatim. Tag a system
block as ephemeral once, save 75% input cost on every subsequent turn.
Cross-provider via Anthropic shape
You can pass non-Anthropic model slugs too — qlaud translates the body to the upstream’s shape automatically:Tool use
Native — same Anthropic shape. Tool definitions,tool_use content blocks,
tool_result content blocks all forwarded.