Direct answer
What is an AI agent SDK?
An AI agent SDK is a code library that helps developers build agent applications with reusable primitives such as agents, model clients, tools, run loops, state, sessions, handoffs, guardrails, tracing, and human interruptions. The SDK accelerates application logic; it does not automatically provide the finished user interface, business workflow, deployment, or operating team.
Reviewed by Raltic Research · Updated August 15, 2026
The short answer first, followed by the operating details and next decision.
The SDK supplies runtime primitives; the product team supplies the surrounding application.
- 01
Define
Agent instructions, models, tools, output schemas, and guardrails.
- 02
Coordinate
Loops, handoffs, graphs, state, sessions, and interruptions.
- 03
Inspect
Events, traces, usage, errors, and application-specific eval hooks.
- 04
Productize
Authentication, UI, permissions, deployment, alerts, and ownership.
What primitives do agent SDKs provide?
The common core is an agent definition, a run loop, tools, state, and extension points.
OpenAI Agents SDK emphasizes agents, tools, handoffs, guardrails, sessions, tracing, and human approval. Google ADK and Microsoft Agent Framework add broader graph, multi-agent, deployment, and evaluation patterns. Exact capabilities and language support change, so compare the current release rather than the category label.
- 01Agent and model configuration
- 02Tools and structured inputs
- 03State, sessions, or checkpoints
- 04Handoffs or workflow control
- 05Tracing and evaluation hooks
How is an SDK different from a model API?
A model API returns model responses; an agent SDK manages more of the loop around those calls.
Developers can call a model API directly and own tool dispatch, retries, context, state, and stopping conditions. An SDK packages common patterns so the team writes less orchestration code and follows a consistent runtime model.
How is an SDK different from a platform?
A platform usually supplies more runtime, deployment, observability, governance, or user-facing workflow.
The boundary is not absolute. Some vendors offer an SDK plus hosted runtime and evaluation services. Ask what the team must still build, deploy, monitor, secure, and explain to users after adopting the SDK.
- 01Application UI
- 02Authentication and authorization
- 03Durable hosting
- 04Business review process
- 05Operational support
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