a16z Podcast

Building APIs for Developers and AI Agents

Episode Summary

Stainless founder Alex Rattray joins a16z partner Jennifer Li to talk about the future of APIs, SDKs, and the rise of MCP (Model Context Protocol). Drawing on his experience at Stripe—where he helped redesign API docs and built code-generation systems—Alex explains why the SDK is the API for most developers, and why high-quality, idiomatic libraries are essential not just for humans, but now for AI agents as well.

Episode Notes

Stainless founder Alex Rattray joins a16z partner Jennifer Li to talk about the future of APIs, SDKs, and the rise of MCP (Model Context Protocol). Drawing on his experience at Stripe—where he helped redesign API docs and built code-generation systems—Alex explains why the SDK is the API for most developers, and why high-quality, idiomatic libraries are essential not just for humans, but now for AI agents as well.

They dive into:

Timecodes: 

0:00 – Introduction: APIs as the Dendrites of the Internet

1:49 – Building API Platforms: Lessons from Stripe

3:03 – SDKs: The Developer’s Interface

6:16 – The MCP Model: APIs for AI Agents

9:23 – Designing for LLMs and AI Users

13:08 – Solving Context Window Challenges

16:57 – The Importance of Strongly Typed SDKs

21:07 – The Future of API and Agent Experience

24:45 – Lessons from Leading API Companies

26:14 – Outro and Disclaimers

Resources: 

Find Alex on X: https://x.com/rattrayalex

Find Jennifer on X: https://x.com/JenniferHli

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