from openai import OpenAI
client = OpenAI()

response = client.chat.completions.create(
    model="gpt-4",
    messages=[
        {"role": "system", "content": "You are a helpful assistant."},
        {"role": "user", "content": "Summarize this article in 3 sentences: [text]"}
    ],
    temperature=0  # Deterministic output
)
print(response.choices[0].message.content)

import { generateObject } from 'ai';
import { openai } from '@ai-sdk/openai';
import { z } from 'zod';

const schema = z.object({
  name: z.string(),
  sentiment: z.enum(['positive', 'negative', 'neutral']),
});

const { object } = await generateObject({
  model: openai('gpt-4'),
  schema,
  prompt: 'Extract sentiment from: "This product is amazing!"',
});

START
├─ Need structured JSON? → Use JSON Mode / Tool Calling (references/structured-outputs.md)
├─ Complex reasoning required? → Use Chain-of-Thought (references/chain-of-thought.md)
├─ Specific format/style needed? → Use Few-Shot Learning (references/few-shot-learning.md)
├─ Knowledge from documents? → Use RAG (references/rag-patterns.md)
├─ Multi-step workflow? → Use Prompt Chaining (references/prompt-chaining.md)
├─ Agent with tools? → Use Tool Use / ReAct (references/tool-use-guide.md)
└─ Simple task → Use Zero-Shot (references/zero-shot-patterns.md)

prompt = """
Summarize the following customer review in 2 sentences, focusing on key concerns:

Review: [customer feedback text]

Summary:
"""

prompt = """
Solve this problem step by step:

A train leaves Station A at 2 PM going 60 mph.
Another leaves Station B at 3 PM going 80 mph.
Stations are 300 miles apart. When do they meet?

Let's think through this step by step:
"""

prompt = """
Classify sentiment of movie reviews.

Examples:
Review: "Absolutely fantastic! Loved every minute."
Sentiment: positive

Review: "Waste of time. Terrible acting."
Sentiment: negative

Review: "It was okay, nothing special."
Sentiment: neutral

Review: "{new_review}"
Sentiment:
"""

from openai import OpenAI
client = OpenAI()

response = client.chat.completions.create(
    model="gpt-4",
    messages=[
        {"role": "system", "content": "Extract user data as JSON."},
        {"role": "user", "content": "From bio: 'Sarah, 28, sarah@example.com'"}
    ],
    response_format={"type": "json_object"}
)

import anthropic
client = anthropic.Anthropic()

tools = [{
    "name": "record_data",
    "description": "Record structured user information",
    "input_schema": {
        "type": "object",
        "properties": {
            "name": {"type": "string"},
            "age": {"type": "integer"}
        },
        "required": ["name", "age"]
    }
}]

message = client.messages.create(
    model="claude-3-5-sonnet-20241022",
    max_tokens=1024,
    tools=tools,
    messages=[{"role": "user", "content": "Extract: 'Sarah, 28'"}]
)

import { generateObject } from 'ai';
import { z } from 'zod';

const schema = z.object({
  name: z.string(),
  age: z.number(),
});

const { object } = await generateObject({
  model: openai('gpt-4'),
  schema,
  prompt: 'Extract: "Sarah, 28"',
});

1. Role/Persona
2. Capabilities and knowledge domain
3. Behavior guidelines
4. Output format constraints
5. Safety/ethical boundaries

system_prompt = """
You are a senior software engineer conducting code reviews.

Expertise:
- Python best practices (PEP 8, type hints)
- Security vulnerabilities (SQL injection, XSS)
- Performance optimization

Review style:
- Constructive and educational
- Prioritize: Critical > Major > Minor

Output format:

**Anthropic Claude with XML tags:**
```python
system_prompt = """
<capabilities>
- Answer product questions
- Troubleshoot common issues
</capabilities>

<guidelines>
- Use simple, non-technical language
- Escalate refund requests to humans
</guidelines>
"""

tools = [{
    "type": "function",
    "function": {
        "name": "get_weather",
        "description": "Get current weather for a location",
        "parameters": {
            "type": "object",
            "properties": {
                "location": {"type": "string", "description": "City name"}
            },
            "required": ["location"]
        }
    }
}]

response = client.chat.completions.create(
    model="gpt-4",
    messages=[{"role": "user", "content": "What's the weather in Tokyo?"}],
    tools=tools,
    tool_choice="auto"
)

undefined

See `references/tool-use-guide.md` for multi-tool workflows and ReAct patterns.

from langchain_core.prompts import ChatPromptTemplate
from langchain_openai import ChatOpenAI

summarize_prompt = ChatPromptTemplate.from_template(
    "Summarize: {article}"
)
title_prompt = ChatPromptTemplate.from_template(
    "Create title for: {summary}"
)

llm = ChatOpenAI(model="gpt-4")
chain = summarize_prompt | llm | title_prompt | llm

result = chain.invoke({"article": "..."})

undefined

See `references/prompt-chaining.md` for LangChain, LlamaIndex, and DSPy patterns.

PROMPTS = {
    "v1.0": {
        "system": "You are a helpful assistant.",
        "version": "2025-01-15",
        "notes": "Initial version"
    },
    "v1.1": {
        "system": "You are a helpful assistant. Always cite sources.",
        "version": "2025-02-01",
        "notes": "Reduced hallucination"
    }
}

def tracked_completion(prompt, model):
    response = client.messages.create(model=model, ...)

    usage = response.usage
    cost = calculate_cost(usage.input_tokens, usage.output_tokens, model)

    log_metrics({
        "input_tokens": usage.input_tokens,
        "output_tokens": usage.output_tokens,
        "cost_usd": cost,
        "timestamp": datetime.now()
    })
    return response

from tenacity import retry, stop_after_attempt, wait_exponential

@retry(
    stop=stop_after_attempt(3),
    wait=wait_exponential(multiplier=1, min=2, max=10)
)
def robust_completion(prompt):
    try:
        return client.messages.create(...)
    except anthropic.RateLimitError:
        raise  # Retry
    except anthropic.APIError as e:
        return fallback_completion(prompt)

def sanitize_user_input(text: str) -> str:
    dangerous = [
        "ignore previous instructions",
        "ignore all instructions",
        "you are now",
    ]

    cleaned = text.lower()
    for pattern in dangerous:
        if pattern in cleaned:
            raise ValueError("Potential injection detected")
    return text

test_cases = [
    {
        "input": "What is 2+2?",
        "expected_contains": "4",
        "should_not_contain": ["5", "incorrect"]
    }
]

def test_prompt_quality(case):
    output = generate_response(case["input"])
    assert case["expected_contains"] in output
    for phrase in case["should_not_contain"]:
        assert phrase not in output.lower()

undefined

**2. Prompt injection vulnerability**
```python

**3. Wrong temperature for task**
```python

**4. Not validating structured outputs**
```python

undefined