Most "AI email" demos hand the model the whole inbox and hope for the best. That works in a screenshot. It falls apart the first time a real conversation runs past a dozen messages, because every one of those messages — quoted replies, signatures, disclaimers, the recipient's entire previous email pasted underneath theirs — gets shoved into the prompt verbatim. A five-message sales thread can easily be 8,000 tokens of mostly-redundant text. A twenty-message support escalation is a context-window grenade.
The naive fix is "just truncate." Keep the last message, drop the rest. That's worse: the agent loses the thing it actually needs, which is what was already agreed, asked, or promised earlier in the thread. The recipient says "yes, the 14th works" and your agent has no idea what the 14th refers to.
The right move is summarization for context budget: fetch the full thread, compress the older turns into a running brief, and feed the model only brief + the latest message verbatim. The brief is a few hundred tokens. The latest message is whatever it is. You stay well inside budget and the agent keeps the plot.
I work on the Nylas CLI, so the terminal commands below are the exact ones I reach for when I'm poking at a live Agent Account. I'll show every step both ways — the raw HTTP call and the CLI equivalent — because that's how I actually debug this stuff.
