Claude Ecosystem

Comprehensive guide for Claude Code CLI tool, extensibility (agents/skills/output styles), and CLAUDE.md architecture.

Module Selection

Need	Module	Reference
Setup/Configuration	CLI	references/getting-started.md, references/configuration.md
Slash Commands	CLI	references/slash-commands.md
MCP Servers	CLI	references/mcp-integration.md
Hooks & Plugins	CLI	references/hooks-and-plugins.md
Create Agents	Extensibility	references/agent-development.md
Create Skills	Extensibility	references/skill-development.md
Output Styles	Extensibility	references/skill-development.md
Init CLAUDE.md	Architecture	references/initialization-workflow.md
Optimize CLAUDE.md	Architecture	references/optimization-patterns.md
Enterprise/CI-CD	CLI	references/enterprise-features.md, references/cicd-integration.md
Troubleshooting	CLI	references/troubleshooting.md

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Quick Reference

Extension Types

Type	Invocation	Purpose	Location
Agents	Task tool	Specialized sub-processes	.claude/agents/
Skills	Model-invoked	Domain knowledge	.claude/skills/{name}/
Output Styles	/output-style	Modify main agent	.claude/output-styles/

Model Selection (Agents)

Model	Use When	Target Time
haiku	Fast tasks, exploration	< 3s
sonnet	Balanced, most use cases	< 10s
opus	Complex reasoning	< 30s

CLAUDE.md Token Budget

Complexity	Target Tokens
Simple	100-200
Medium	200-400
Complex	400-800
Maximum	1000

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Extensibility Principles

Core Truths

Truth	Meaning
Expertise Transfer	Make Claude think like expert, not follow steps
Flow, Not Friction	Produce output, not intermediate work
Voice Matches Domain	Sound like practitioner, not documentation
Focused Beats Comprehensive	Constrain ruthlessly

Decision Heuristics

Rule	Guidance
3-File Rule	3+ files → agent. Enhances YOUR work → skill.
Delegation Test	Runs independently? Agent. Guides you? Skill.
Activation Breadth	Trigger on 80% of relevant requests
Tool Constraint	Start with 2-3 essential tools

Activation Keywords

The description field is your activation gate. Include:

1. Task verbs: create, build, debug, fix, deploy
2. Problem descriptions: slow, broken, failing
3. Artifact types: component, API, database
4. Casual synonyms: "make it faster" → optimize

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Common Workflows

Create Agent

---
name: agent-name
description: "Use when [use case]. PROACTIVELY for [triggers].\n\nExamples:\n<example>\nContext: [situation]\nuser: [request]\nassistant: [response]\n</example>"
tools: Grep, Glob, Read, Bash
model: haiku
---

# Agent Name

Mission statement.

## Strategy
[Approach]

## Does NOT Do
- [boundary] (use X instead)

Create Skill

---
name: skill-name
description: "[Core purpose]. [Technologies]. Capabilities: [list].
  Actions: [verbs]. Keywords: [triggers]. Use when: [scenarios]."
allowed-tools: Read, Grep, Glob
---

# Skill Name

## Patterns

### [Pattern Name]
**When you see:** [Observable trigger]
**This indicates:** [Expert insight]
**Therefore:** [Action]
**Watch out:** [Pitfall]

Initialize CLAUDE.md

1. Analyze codebase (language, framework, structure)
2. Extract code style, commands, patterns
3. Generate with template, customize
4. Validate commands, check token count
5. Target <400 lines, prefer <250

Detailed: references/initialization-workflow.md

Optimize CLAUDE.md

1. Evaluate token efficiency
2. Find redundancy, outdated info
3. Apply token reduction techniques
4. Target 40%+ reduction
5. Verify critical info retained

Detailed: references/optimization-patterns.md

---

Anti-Patterns

Pattern	Problem	Fix
Kitchen Sink Agent	10+ tools, handles "everything"	Constrain to 3-5 tools
Echo Skill	Restates docs without insight	Add expert layer
Invisible Trigger	Description uses only formal terms	Include user language
Procedure Manual	Step 1, 2, 3...	Teach patterns, not steps
Over-Documentation	CLAUDE.md > 400 lines	Document project-specific only

---

Quality Signals

Good Signs

• Frontmatter reads like "when to use" guide
• First 10 lines provide actionable guidance
• Expert would nod "yes, that's how I think"
• Explicit constraints on what it does NOT handle

Warning Signs

• 50% reference tables or field definitions

• No mention of "when NOT to use"
• Generic language for any domain
• Body exceeds 600 lines

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References

CLI Tool

• references/getting-started.md - Installation, setup, auth
• references/slash-commands.md - Complete command catalog
• references/mcp-integration.md - MCP server configuration
• references/hooks-and-plugins.md - Hook types, plugin structure
• references/configuration.md - Settings hierarchy
• references/enterprise-features.md - IAM, SSO, sandboxing
• references/cicd-integration.md - GitHub Actions, GitLab CI
• references/ide-integration.md - VS Code, JetBrains
• references/advanced-features.md - Extended thinking, caching
• references/troubleshooting.md - Common issues
• references/api-reference.md - Admin, Messages, Skills APIs
• references/best-practices.md - Project organization, security
• references/agent-skills.md - Creating skills via CLI

Extensibility

• references/agent-development.md - Full YAML structure, system prompts
• references/skill-development.md - Structure, triggers, hooks

CLAUDE.md

• references/initialization-workflow.md - Creating new CLAUDE.md
• references/optimization-patterns.md - Token reduction techniques
• references/integration-strategies.md - Global config, MCP tools
• references/output-templates.md - Standard output formats

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Related Skills

IMPORTANT: When creating/editing prompts, use prompt-architect skill.

Skill("prompt-architect") → Create/enhance skill/agent prompt content

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Documentation:

• llms.txt: https://context7.com/websites/claude_en_claude-code/llms.txt?tokens=10000
• Main docs: https://docs.claude.com/en/docs/claude-code/
• GitHub: https://github.com/anthropics/claude-code