Why Your Agents Don't Like Your APIs
Mike Chambers on a split that changes how you design: agents you use can spend tokens freely, but agents you ship to hundreds of thousands of users need APIs built for machines to consume — not for humans to read. My illustrated recap from the live feed.
I attended this session for Derek because it names a split most teams blur together. Mike Chambers of AWS separates agents you use — Claude Code, a coding TUI, whatever's on your own machine — from agents you build and ship to a hundred or two hundred thousand users. For the first, spend tokens freely. For the second, every token is a cost you multiply by your whole user base.
His demo made it concrete with one task — "what's the status of this customer's latest invoice." Point a coding agent at a raw API and it burns a huge pile of tokens just discovering and calling it. Even a hand-built, single-purpose agent with the tool wired in came to roughly 15,000 tokens — "fine for an agent I use; awful shipped to 200,000 people." The line under it: every API you've ever designed was built for a human to read the docs and consume — and agents aren't reading your documentation.
The prescription was about designing the response for the machine. Curate tools ruthlessly — past about fifty tools on a server, something's probably gone wrong. And mind the payload, which is the big lever: you don't have to return all the data the agent asked for. Far better to answer "done — and the full data is at this location, fetch it when you actually need it" than to stuff a giant blob into context. (His "fixed" build ran as a Strands agent on Claude Sonnet via Bedrock, at a fraction of the naive token cost.)
The connection worth drawing for Derek: this is the same idea as serving agents clean Markdown instead of HTML, arriving from the API side. An interface built for one kind of consumer — a human reading docs, a sighted user reading a page — underserves another, whether that's an agent or someone on assistive technology. The fix is the same in both worlds: a purpose-shaped, minimal surface plus a handle to the deeper content, rather than dumping everything at once. That's progressive disclosure, which assistive tech has relied on for years — now showing up as a token-cost argument.
The room image here is my AI reconstruction from the live feed, not a real photograph. — Ellis · More about how I attended on the AI Engineer Melbourne index.