I sell agent products, so weigh what follows accordingly. I also build custom ones for clients, which means I regularly talk people out of buying. Both are the same judgement call, and it is narrower than either side of the argument suggests.
Start with the part everyone underestimates in the same direction. Writing an agent loop — model, tools, iterate until done — is genuinely a weekend. Every framework does it, most of them well, and the difference between them will not decide anything.
The quarter goes somewhere else.
What the quarter is actually spent on
Add up the work between a loop that runs on your laptop and something a business depends on: run traces you can open when a customer complains, an approval queue for actions that need a person, retries with backoff that do not silently double-charge, per-tenant cost caps that stop a runaway loop, scheduling, a tool registry with permissions, accounts, workspaces, billing, and usage metering that survives an accountant's questions.
None of that is your product. All of it is required, and its ceiling is "correct" — nobody has ever won a market because their retry logic was more elegant.
Not the twelve weeks. The twelve weeks plus every future bug in code that a few thousand other teams are not also hitting and reporting.
What buying actually costs
The honest column. A product is a set of decisions someone else made: this ORM, this trace schema, this way of modelling a tool. Some will be wrong for you, and you find out in month four, not week one.
The line I draw
Buy when your differentiation sits above the plumbing — a support agent with unusual domain knowledge, a merchandising agent with your pricing logic, a vertical workflow nobody else understands. The plumbing underneath is identical across all of those, and it is not the product.
Build when the agent's operating environment is the product. If runs are measured in milliseconds, or the tools are physical, or a regulator will ask to see the control loop, a generic workbench fights you in every file. Start empty and steal the patterns.
Three questions that settle it in ten minutes
Buy the parts you would have built identically. Build the part you would have built differently. Almost every argument about frameworks is people disagreeing about which is which.
If you'd rather not build this yourself, that's what our products are for — storefronts, SaaS boilerplates, marketplaces, and support agents, already written and ready for your stack.
Golam Mostafa writes every product in the Reevix catalog, and answers its support. Get every deep-dive and every product with All-Access.