TL;DR
  • Anthropic’s November 2025 prompt-engineering guide explicitly downgrades XML tags and heavy role-play for current models — not because they stopped working, but because clear, explicit language now does the same job with less overhead
  • “Longer is better” was never the rule. Anthropic’s own guidance is the opposite: minimum structure that reliably gets the result
  • The bigger change isn’t a prompting trick — it’s the rise of context engineering, a term Tobi Lütke and Andrej Karpathy popularized in mid-2025 and Anthropic now treats as the layer prompting sits inside
  • None of this touches hallucination. A well-structured prompt produces a confident wrong answer exactly as fluently as a sloppy one — verification still has to happen somewhere

A lot of “prompt engineering guides” still in circulation are, functionally, 2023 advice with a 2026 date stamp. The tell is usually XML tags presented as mandatory and a persona template glued to the top of every example. Anthropic’s own team published updated guidance on this in November 2025, and it reads less like a hype piece and more like a partial retraction of earlier advice. Source: Anthropic, “Prompt engineering best practices for 2026,” claude.com/blog, Nov 10 2025

❌ 2023-2025 advice

Wrap every prompt section in XML tags — it’s how you get structure and precision.

Established What Anthropic says now

XML tags still help with extremely mixed content or when you need hard boundaries, but current models parse plain structure — headings, whitespace, explicit phrases like “using the information below” — about as well. For most prompts, the tags are now overhead rather than a requirement.

❌ 2023-2025 advice

Give the model an elaborate persona: “You are a world-renowned expert who never makes mistakes.”

Established What Anthropic says now

Anthropic’s guidance now explicitly warns against over-constrained roles, on the grounds that a narrow persona can limit rather than sharpen the response. Being direct about the perspective you want — risk tolerance, long-term growth, whatever the actual angle is — tends to beat assigning a character.

❌ 2023-2025 advice

More detail, more examples, more caveats — a longer prompt is a more controlled prompt.

Established What Anthropic says now

The stated principle is the opposite: the best prompt is the one that reaches the goal with the least structure necessary, not the most. Anthropic’s own troubleshooting notes treat over-engineering as a named failure mode, not a safe default.

Manual chain-of-thought hasn’t disappeared, but Anthropic now frames it as a fallback for when extended thinking isn’t available, not the default move for every complex task.

Paraphrased from Anthropic’s Nov 2025 prompt engineering guide

Why “context engineering” isn’t just a rebrand

The more consequential shift isn’t a technique swap, it’s a change in what the leverage point is. The term “context engineering” was popularized in June 2025 — Shopify’s Tobi Lütke used it first, and Andrej Karpathy amplified it about a week later, describing it as the discipline of filling the context window with exactly the right information for the next step. Source: reporting on Lütke and Karpathy’s June 2025 posts, aggregated via autogpt.net, July 2026 — Probable, original posts not independently re-verified here

Established Anthropic has folded this into its own guidance rather than treating it as a competing idea. Its Claude Sonnet 5 documentation states plainly that prompting is converging with context engineering for current-generation models — less scaffolding, more curation of what the model actually sees. In practice that means the highest-leverage decision often isn’t how you phrase the ask, it’s what documents, history, and tool outputs are sitting in the context window when you ask it. Source: Anthropic, claude.com/blog, “the new rules of context engineering for Claude 5-generation models”

Probable Industry surveys are already reflecting the shift, though these numbers come from vendor and industry reports rather than peer-reviewed research: one widely cited 2026 report on context management found a large majority of IT and data leaders now consider prompt engineering alone insufficient for AI at scale. Treat the specific percentage as directional rather than verified.

What this actually means for how you work

You don’t need to abandon prompting skills — Anthropic is explicit that a well-built prompt is still the basic unit inside a good context. But if your process is “tweak the wording until it’s better,” and you’re not also asking what’s missing from the model’s context — the right file, the right prior turn, the right retrieved document — you’re optimizing the smaller lever.


What better prompting still doesn’t solve

None of the above touches the thing that actually causes expensive mistakes: a model producing a fluent, confident, wrong answer. Anthropic’s own troubleshooting guidance names this directly and offers one concrete lever — explicitly giving the model permission to say it doesn’t know rather than guess — which it credits with reducing (not eliminating) the problem.

That’s a mitigation, not a fix. A cleanly structured, well-contexted, role-appropriate response has no less surface confidence when it’s wrong than when it’s right — arguably more, because good prompting also improves fluency and formatting, which are exactly the signals people unconsciously use to judge trustworthiness. If a response will be published, sent to a client, or used to make a decision, the verification step doesn’t get engineered away by a better prompt. It just moves later in the process, where it costs more to fix.


Where Claude, GPT, and Gemini actually differ right now

Flagship lineups moved fast through 2025 and into 2026, so a comparison table from even a year ago is already listing retired models. Here’s where things stand with current generations, without vendor benchmark cherry-picking:

Model familyWhere it’s currently strongestWorth knowing
Claude (Sonnet 5 / Opus 4.7) Agentic workflows — planning, tool use, and self-verification loops (write a test, apply a fix, re-check) rather than single-shot answers Anthropic’s own docs now treat prompting as inseparable from context engineering for this generation, which shows up as less prompt scaffolding being needed to get consistent behavior
GPT (5.5 and Codex variants) Fast-moving release cadence and strong benchmark scores on reasoning and terminal/coding tasks per OpenAI’s own reporting Vendor-reported benchmark comparisons against competing models should be read as self-published unless independently replicated
Gemini 3.1 Pro / Flash Long-context and multimodal tasks, plus tight integration with Google’s own tools and real-time retrieval Real-time retrieval is also a source of recency bias — the model can over-weight whatever’s newest rather than whatever’s most authoritative
Model naming current as of August 2026; this category shifts every few months, so check each vendor’s release notes before citing version numbers.

FAQ

Is prompt engineering as a skill becoming obsolete?

No, but its scope narrowed. Anthropic frames it as a building block inside the larger discipline of context engineering rather than the whole game — worth learning, not worth treating as the only lever.

Should I stop using XML tags in my prompts?

Not entirely — they still help with genuinely mixed, complex content or when you need unambiguous boundaries. For everyday prompts, clear plain-language structure now does comparable work with less overhead.

Does chain-of-thought prompting still matter if a model has “extended thinking”?

It’s now the fallback rather than the default — useful when extended thinking isn’t available or when you specifically need reasoning you can inspect, rather than something to bolt onto every complex prompt automatically.

What’s the fastest way to reduce hallucinated answers?

Explicitly tell the model it’s allowed to say it doesn’t know rather than guess. It’s a small addition with a documented effect on reliability, though it reduces the problem rather than eliminating it.

What is context engineering, in one sentence?

Deliberately controlling everything the model sees before it answers — documents, history, tool outputs, system instructions — rather than just the wording of the final instruction.


TM

Tom Morgan

Covers applied AI tooling and workflow design for BestPrompt.art. Sourcing for this piece leans on Anthropic’s own published documentation, so it reflects Claude’s ecosystem more thoroughly than GPT’s or Gemini’s — read the model comparison section with that scope in mind.

No sponsorship: none of the tools or vendors named in this article paid for placement.

Most of what makes a prompt “good” in 2026 was already true in 2023: be specific, give a reason, show rather than tell. What changed is everything people bolted on top of that — and the model makers are the ones now saying so.