Rig 0.16.0 is now live - Rust MCP SDK support, reasoning support and more!

[joshua-mo-143]

Rig 0.16.0 is now officially released on Crates.io!

Breaking changes

• VectorStoreIndex trait now takes the VectorSearchRequest, which we will be using as a stable API for the future and building on for the purposes of ergonomics.
• Completion usage while streaming is now returned as the final item in a streaming response. Although you can still technically get it the regular way, you'll probably want to do it this way as it's much more ergonomic.
• ToolResultContent is now serde-tagged
• Every model provider integration now has a ClientBuilder

Additions

• Updated GROK_4 model constant
• The official Rust MCP SDK is now supported!!! 🥳 🎉
• Some optimisations when using OneOrMany
• Support for reasoning/thinking
• Add extra tracing when there is no data (ie the tool hasn't been called).
• PromptResponse type is now public. Useful if you need token usage info.

Fixes

• OpenAI tool call IDs are now properly propagated meaning multiple tool calls in a row shouldn't fail
• Some minor changes have been made to the OpenAI streaming integrations to improve stability/business logic

Migration

• If you are using Client::from_url(), you will now need to use Client::builder() and add it in from there. Otherwise if you don't care about changing your inner HTTP client or changing the base URL, you can still use Client::new(<api_key_here>) or Client::from_env() to achieve the same result as you normally would.
• VectorStoreIndex and VectorStoreIndexDyn now take a rig::vector_search::VectorSearchRequest, instead of a query and max result size. This has been done to enable much more ergonomic requesting in the future. Please see any of the vector_search examples for practical usage.
• The final response of a completion stream now yields the completion usage from the stream itself. You may wish to adjust your code to account for this.
• The mcp-core integration is now officially deprecated because the official Rust MCP SDK is now supported as it has feature parity. You will need to ensure you have moved to the rmcp integration (rmcp feature flag) by Rig 0.18.0 at the earliest.
• ToolResultContent is now #[serde(tag = "type")]. If you're storing the serialized Rig structs anywhere as JSON, you may need to account for this and write a script to backfill your stored JSON.