Prompt Engineering in 2025

Working with GPT‑4 “4.0” and the new GPT‑4.5

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1. Why This Guide?

GPT‑4.0 pushed LLM reasoning to new heights; GPT‑4.5 (Feb 2025) widens the context window to 256 k tokens, lowers latency, adds richer multimodal understanding, and streams structured JSON through stronger function‑calling. Prompt quality now drives even bigger gains because the model can “see” far more text and follow stricter schemas. Analytics Vidhya

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2. The Three Chat Roles (unchanged, still crucial)

Role	What you put here	4.0 & 4.5 tips
system	Global persona & constraints	Use one to anchor style across 50 k‑token conversations; 4.5 will otherwise drift.
user	The actual task / question	Keep it crisp; the bigger window tempts verbosity.
assistant	Optional demonstrations of ideal replies	4.5 treats these as high‑authority examples—great for style‑anchoring.

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3. Prompting Basics Recap

Minimal prompt

csharpCopyEditThe sky is

Likely completion: “blue.”
Improved

csharpCopyEditComplete the sentence:
The sky is

Output: “blue during the day and dark at night.”
One extra line (“Complete the sentence”) clarifies the goal—classic prompt engineering.

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4. Zero‑Shot vs. Few‑Shot

Technique	Format	When to use
Zero‑shot	Question?	Quick look‑ups; simple tasks.
Few‑shot	Q / A pairs or label examples	Niche domains, custom style, small datasets.

Few‑shot example (sentiment):

csharpCopyEditThis is awesome! // Positive
This is bad! // Negative
Wow that movie was rad! // Positive
What a horrible show! //

Model → “Negative”

Few‑shot is more powerful in GPT‑4.5 because those demonstrations can sit alongside hundreds of pages of background docs without blowing the token limit.

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5. New Super‑Powers in GPT‑4.5

Feature	Why it matters	Source
256 k context	Paste entire manuals + examples + your question in one go.	Analytics Vidhya
Lower latency	Despite the size, 4.5 streams answers faster than 4.0‑turbo in most benchmarks.	Analytics Vidhya
Emotionally nuanced replies	Conversations feel warmer; great for user‑facing apps.	Business Insider
Robust function‑calling	Partial‑JSON streaming keeps responses parseable in real time.	Learn R, Python & Data Science Online
Reduced hallucinations	37 % drop vs GPT‑4o, boosting factual tasks.	Financial Times

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6. Prompt Formatting Patterns that Shine in 4.5

1. Instruction + Schema pgsqlCopyEditYou are a tax‑law assistant. Answer the user in this JSON schema: { "risk":"", "citation":"" } The model streams valid JSON you can parse on the fly.
2. Chain‑of‑Thought (CoT) arduinoCopyEditThink step‑by‑step, then give a one‑line answer. 4.5’s reasoning trace is clearer; hide it afterward if you only need the final.
3. Multimodal pgsqlCopyEdit<image:invoice.jpg> Extract the due date and total in JSON.

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7. Practical Prompt‑Engineering Checklist (2025 edition)

• Clear task (“Summarize”, “Classify”, “Answer in Spanish”, etc.)
• System persona set (tone, constraints)
• Desired output format (Markdown, JSON keys, word limit)
• Examples or edge‑case demos (few‑shot)
• Keep within token budget (even 256 k will truncate if you overdo it)
• Automated tests—run a prompt suite to catch regressions when you tweak wording.

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8. Example: Upgrading a Prompt for GPT‑4.5

Goal: Summarize a 50‑page onboarding PDF into three bullet points and a table of action items.

textCopyEditsystem: You are a concise HR assistant.
user: Summarize the attached employee handbook into:
- Three key‑takeaway bullets (≤20 words each)
- A Markdown table with “Task”, “Owner”, “Due Date”
Return valid Markdown only.
assistant (demo): 
- Key points …
| Task | Owner | Due Date |
| --- | --- | --- |
| Example | HR | 2025‑06‑01 |
user: <full PDF text here>

Even at 50 pages (~20 k tokens) plus prompt and examples, you are far under 4.5’s 256 k limit, and the JSON‑like table is easy to parse.

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9. Choosing Between GPT‑4.0 and GPT‑4.5

Need	Use 4.0	Use 4.5
Cheapest drafts / quick chats	✔️
Massive docs, legal contracts, RAG		✔️
Emotionally intelligent UX copy		✔️
Strict JSON streaming & tool calls		✔️
Latency‑sensitive but small context	✔️

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10. The Road Ahead

Rumors point to GPT‑5 later in 2025, but the day‑to‑day win right now is learning to layer instructions, context, and examples so today’s models can reason at full blast. Treat every prompt as code: document it, test it, version‑control it.

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TL;DR

1. Prompt clarity still rules.
2. Use system / user / assistant roles intentionally.
3. Leverage 4.5’s 256 k window and streaming JSON for ambitious workflows.
4. Add examples for niche or creative styles.
5. Iterate, measure, repeat—great prompts age like fine wine.

Happy prompting!