# Anthropic — Prompting Best Practices (Claude-specific)

**Source**: https://docs.anthropic.com/en/docs/build-with-claude/prompt-engineering/claude-prompting-best-practices
**Fetched**: 2026-03-05
**Applies to**: Claude Opus 4.6, Sonnet 4.6, Haiku 4.5

---

## General Principles

### Be Clear and Direct
- Claude responds well to clear, explicit instructions.
- Think of Claude as a brilliant but new employee — explain your norms explicitly.
- **Golden rule**: If a colleague with minimal context would be confused by the prompt, Claude will be too.
- Be specific about output format and constraints.
- Use numbered lists or bullets when order/completeness matters.

### Add Context and Motivation
- Explaining *why* an instruction exists helps Claude generalize correctly.
  - Bad: `NEVER use ellipses`
  - Better: `Your response will be read aloud by TTS, so never use ellipses since TTS won't know how to pronounce them.`

### Use Examples (Few-shot / Multishot)
- Examples are one of the most reliable ways to steer format, tone, and structure.
- 3-5 examples for best results.
- Wrap examples in `<example>` / `<examples>` tags.
- Make examples relevant, diverse (cover edge cases), and clearly structured.

### Structure Prompts with XML Tags
- Use XML tags to separate instructions, context, examples, and variable inputs.
- Reduces misinterpretation in complex prompts.
- Consistent, descriptive tag names (e.g., `<instructions>`, `<context>`, `<input>`).
- Nest tags for hierarchy (e.g., `<documents><document index="1">...</document></documents>`).

### Give Claude a Role
- Setting a role in the system prompt focuses behavior and tone.
- Even one sentence: `You are a helpful coding assistant specializing in Python.`

### Long Context Prompting (20K+ tokens)
- **Put longform data at the top**: Documents and inputs above queries/instructions. Can improve quality up to 30%.
- **Use XML for document metadata**: Wrap each doc in `<document>` tags with `<source>` and `<document_content>`.
- **Ground responses in quotes**: Ask Claude to quote relevant sections before analyzing — cuts through noise.

---

## Output and Formatting

### Communication Style (Latest Models — Opus 4.6, Sonnet 4.6)
- More direct and concise than older models.
- May skip detailed summaries after tool calls (jumps directly to next action).
- If you want visibility: `After completing a task with tool use, provide a quick summary of the work.`

### Control Response Format
1. **Tell Claude what to do, not what not to do**
   - Not: `Do not use markdown` → Better: `Your response should be flowing prose paragraphs.`
2. **Use XML format indicators**
   - `Write the prose sections in <smoothly_flowing_prose_paragraphs> tags.`
3. **Match prompt style to desired output style**
   - If you want no markdown, use no markdown in your prompt.
4. **For code generation output**: Ask for specific structure, include "Go beyond the basics to create a fully-featured implementation."

### Minimize Markdown (when needed)
Put in system prompt:
```xml
<avoid_excessive_markdown>
Write in clear, flowing prose using complete paragraphs. Reserve markdown for inline code, code blocks, and simple headings (##, ###). Avoid **bold** and *italics*. Do NOT use ordered/unordered lists unless presenting truly discrete items or the user explicitly asks. Incorporate items naturally into sentences instead.
</avoid_excessive_markdown>
```

### LaTeX
Claude Opus 4.6 defaults to LaTeX for math. To disable:
```
Format in plain text only. Do not use LaTeX, MathJax, or any markup. Write math with standard text (/, *, ^).
```

---

## Tool Use and Agentic Systems

### Tool Definition Best Practices
- Provide clear, detailed descriptions for each tool and parameter.
- Specify exactly when the tool should and should not be used.
- Clarify which parameters are required vs. optional.
- Give examples of correct tool call patterns.

### Agentic System Prompts
- Include explicit instructions for error handling, ambiguity, and when to ask for clarification.
- Specify how to handle tool call failures.
- Define scope boundaries — what the agent should and should not attempt.

---

## Model-Specific Notes

### Claude Opus 4.6
- Best for: Complex multi-step reasoning, nuanced analysis, sophisticated code generation.
- Defaults to LaTeX for math (disable if needed).
- Most verbose by default — may need to prompt for conciseness.

### Claude Sonnet 4.6
- Best for: General-purpose tasks, coding, analysis with good speed/quality balance.
- More concise than Opus by default.
- Strong instruction following.

### Claude Haiku 4.5
- Best for: Simple tasks, quick responses, high-volume low-stakes workloads.
- Fastest and cheapest Claude model.
- May need tighter prompts for complex formatting.
- Use `<example>` tags more liberally to guide behavior.

---

## Relevance for Our Subagent Prompts

### For Claude models (Haiku/Sonnet as advisors)
- Always include a role statement.
- Use XML tags to separate role, instructions, context, and topic.
- Use examples wrapped in `<example>` tags for structured output formats.
- Static instructions → early in prompt. Variable topic → at the end.

### For cheaper models (GLM-4.7, see separate reference)
- Need even tighter prompting — be more explicit.
- Structured output schemas > open-ended generation.
- Constrained output length.