announcement aidev BREAKING SIG 4/5

OpenRouter: tool blocks widened to support MCP tool references, VoyageAI provider option

OpenRouter's Messages API tool blocks (MessagesToolAdditionBlock, MessagesToolRemovalBlock) now accept a union of tool_reference, mcp_tool_reference, and mcp_toolset_reference, with cache_control support added. Existing tool_reference payloads remain valid. The ProviderName enum and ProviderOptions gain new entries including VoyageAI.

PUBLISHED2026-07-24
OBSERVED2026-08-21
AGE1mo
SOURCES1
  • MessagesToolAdditionBlock and MessagesToolRemovalBlock: tool field widened from a single tool_reference object to a union of tool_reference, mcp_tool_reference (name + server_name), and mcp_toolset_reference (server_name). The type property moved into the tool_reference variant. Existing {"type": "tool_reference", "name": "..."} payloads remain valid. cache_control property added to both blocks.
  • ProviderName enum: new value added, affects multiple endpoints
  • ProviderOptions: new voyageai property added across audio, image, and video endpoints
  • AnthropicCompactionBlock: new encrypted_content property
  • ORAnthropicStopReason: enum value added
api-changebreaking

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