What is an SDK?

Where a raw API is just the wire protocol (endpoints, request/response shapes), an SDK wraps that protocol in idiomatic code for a given language — handling authentication, retries, pagination, and error types so a developer calls a native function instead of constructing HTTP requests by hand. Good SDKs also ship type definitions, so integration errors surface at compile time rather than at runtime. For AI platforms specifically, an SDK typically exposes the primitives needed to build agents: making model calls, defining and registering tools, managing conversation or session state, and streaming responses — turning what would be a large amount of boilerplate into a few documented function calls. This lowers the barrier for third-party developers to build on top of the platform rather than reimplementing its plumbing themselves. SDK design quality directly affects ecosystem growth: a well-documented, stable SDK with clear versioning invites external developers to build integrations and extensions, while a poorly maintained one pushes them toward calling raw APIs or avoiding the platform entirely.