Every Agent Reasoning & Planning comparison and buyer's guide for building AI agents — 35 pieces and counting. Each is a head-to-head or a “best X for Y” roundup with a sources-backed verdict.
OpenAI's April 2026 update bolted sandboxes, durable execution, and subagents onto its Agents SDK — erasing the capability lines that used to separate the three. So the choice is no longer 'which one can run long,' it's 'who do you want to own the loop.'
6 min
Thinking Machines' first open model ships a single knob most builders will skip past — a 0.2-to-0.99 reasoning-effort dial. For a founder, that dial is the actual product: it turns per-call cost, latency, and rate-limit headroom into one number you set.
4 min
One reasons and acts in a single pass. The other retries the same task, writing itself a note on what went wrong. The difference isn't which is smarter — it's whether you have a success signal and can afford the second attempt.
4 min
The loop every tutorial shows you is five lines. The loop that survives a real agent is defined by its edges — four message-shape rules the API enforces with a 400, and four stopping conditions that keep it from running forever.
5 min
Your loop checks for one stop_reason and assumes the rest never happen. Then max_tokens truncates a tool call mid-JSON, pause_turn strands a web search, and a refusal returns empty content — and your agent hangs or crashes. Here's what each of the six actually means and what to do about it.
4 min
GPT-5.6 can spawn and synthesize a swarm of subagents inside a single API call — no orchestration code. That's a gift for prototypes and a trap for anything you need to observe, checkpoint, or route across models.
4 min
Your agent keeps calling the same web search, the same GET, the same DB lookup. Memoize the tool's output keyed on its arguments — but only for the tools where a stale answer can't hurt you.
6 min
Four ways to build an agent on Claude, separated by two questions: who writes the loop, and who runs the box it executes in. A decision matrix for founders who've outgrown the hand-rolled while-loop.
5 min
The reliability trick behind Claude's 'Outcomes' is a loop you can build yourself in about forty lines: a worker produces an artifact, a separate grader scores it against a rubric, and the gap goes back until it passes. Here's the pattern, the code, and the two mistakes that make it useless.
5 min
Anthropic's Outcomes feature wraps an agent in a grader that scores every attempt against a rubric you write, feeds back the gap, and makes it try again — turning a one-shot loop into a self-correcting one. Here's what it does, what it costs, and when a founder should turn it on.
4 min
A deep agent's harness is a context-window and latency tax you pay up front to survive long tasks. On short ones it buys nothing. Here's the line.
5 min
A deep agent is a plain tool-calling loop plus four batteries: a planner, a filesystem, subagents, and context management. Here's create_deep_agent end to end — a working research agent in ~15 lines, then how to add a custom subagent.
4 min
Intercept the tool call, pause for a human approve/deny/edit, then resume from the exact checkpoint — and put the gate where risk lives, not on every call.
5 min
Cloudflare Workflows adds per-step and storage billing no earlier than August 10. The catch for agent builders: the durable-execution habits you were taught — wrap everything in a step, sleep for a day waiting on a human — are the exact shape that now costs money.
4 min
Your agent shouldn't wire money or delete a table without a human saying yes. AI SDK 7 has a first-class approval gate built in — here's the exact code, from a tool that pauses to the second call that resumes it.
4 min
The three multi-agent shapes aren't ranked best-to-worst — they're a single axis. Pick by one question: how much context can you afford to lose between agents?
4 min
Anthropic's new research workbench isn't a smarter model — it's two orthogonal layers, an independent reviewer agent and a reproducibility package, that any agentic pipeline can steal.
4 min
Making several agents argue toward consensus does raise accuracy a few points — but a single model sampled the same number of times, at the same cost, usually matches it, and debate has a failure mode solo sampling doesn't.
4 min
The field spent a year making the orchestrator smarter. Microsoft's Conductor argues the routing layer should be dumb — and spend zero tokens deciding what runs next.
5 min
Telling an agent to review its own reasoning usually makes it worse, not better — and the reason it fails is the same reason Reflexion succeeds. Both come down to one asymmetry: verifying is only easier than generating when the verifier knows something the generator doesn't.
5 min
The point of thinking between tool calls isn't a smarter first plan — a model can plan up front without it. The point is that the model can notice a tool returned something wrong and re-plan on the spot, instead of barreling ahead.
4 min
Mixture-of-Agents wins by quality, not by variety — and a careful 2025 replication found that aggregating repeated samples from your single best model beats mixing different ones in most cases. Here's when an ensemble actually pays, and when it just adds latency.
5 min
Four ways to make an agent fix its own mistakes. Three of them quietly outsource the judgment to the world — and the one that doesn't is the one the research keeps catching in the act.
5 min
A max-step counter is the reflex, and it's necessary — but it caps the damage without fixing the cause. Agents loop because the thing they see never changes, and that's a fixable problem.
5 min
A deep agent is not a new model or a framework breakthrough — it's four cheap, known ingredients that let a plain tool-calling loop survive a long task instead of drifting.
5 min
Both spend N times the inference to make a model smarter. The difference is how they choose the winner — and that choice decides which tasks each one can help.
6 min
Every lab gives you a dial for how hard a model reasons before it answers — through three incompatible interfaces. The surprise is that turning it up isn't always better.
4 min
The topology you pick for your agents is really one decision in disguise — who holds the state and the control — and that single choice sets your token bill, your latency, and whether you can ever debug the thing.
5 min
Pausing an agent for a human approval is the same engineering problem as surviving a crash — both require serializing the run and resuming it later. Here's why, and what each framework gives you.
5 min
They were taught as a quality ladder. They're not — and on reasoning models the ladder is upside down. A field guide to which prompting style actually helps which model.
5 min
Test-time compute makes the model think harder while the user waits. Sleep-time compute moves that thinking off the critical path — but only pays off when the context is known early and reused across queries.
4 min
The architecture decision underneath every agent framework is one most teams skip — and the math of compounding errors says the boring choice is usually right.
5 min
The listicle treats these as three flavors of the same choice. They aren't — two are ends of one axis, and the third sits on a different axis entirely. Pick by your environment, not your vibe.
4 min
A reasoning model is not a better LLM. It is a compute-allocation choice — and the trade only pays off on a specific shape of problem.
4 min
Two of the most-cited essays on agent design say opposite things. They are both right — the disagreement is really about whether your task reads or writes.
5 minNot buyer's guides — the news, teardowns, and explainers behind this topic.