What a framework buys you — and what it costs

Lesson 1 of 4 in The Framework Landscape: Pick One (or None).

Strip the marketing away and every agent framework sells the same three things.

Loop plumbing. The agent loop — call the model, parse tool calls, execute them, append results, repeat until a stopping condition fires — plus the unglamorous edges: retries, rate limits, streaming, timeouts, parallel tool execution.

State. Where the conversation, intermediate results, and memory live between steps — and, in the better frameworks, checkpointing: the ability to persist that state, resume after a crash, or rewind and replay a step.

Tracing hooks. Instrumentation that emits a trace of every model call and tool execution, so you can debug why step 14 went sideways. Increasingly this means OpenTelemetry — though note the OTel GenAI semantic conventions were still marked Development, not stable, as of September 2026.

Key terms: agent framework, agent loop, abstraction debt, vendor lock-in, checkpointing, trace

None of that is free. You pay in three currencies.

Abstraction debt. Every layer between your code and the model is a layer you must understand when it misbehaves. Abstraction debt compounds: a framework that saves you a week in month one can cost you that week back every quarter, fighting defaults you never chose.

Lock-in. Lock-in in agent frameworks is sneakier than an API signature. Your prompts get tuned to the framework’s hidden scaffolding, your state gets persisted in its schema, your evals get wired to its trace format. Swapping frameworks later means re-tuning behaviour, not just renaming imports.

Debugging through layers. When an agent misbehaves, the bug can live in your prompt, the framework’s prompt scaffolding, its tool-schema translation, its retry logic, or the model itself. Each framework layer is another suspect you cannot see without reading its source.

Interactive sorting exercise: You adopted a typical agent framework. Sort each concern: does the framework handle it, or is it still your job?

Interactive checkpoint quiz (2 questions) — open this page in a browser to take it.