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AI Agents•10 min read•October 8, 2025

Building Your First AI Agent: A Practical Guide with Claude Agent SDK

Anthropic recently released comprehensive guidance on building AI agents with their Claude Agent SDK. Let's break down their approach and build a practical example you can implement today.

šŸŽÆ What You'll Learn

By the end of this guide, you'll understand the core principles of agent development and have a working example of a personal research assistant that can:

  • • Search and analyze documents in your file system
  • • Generate research summaries and reports
  • • Verify its own work and catch errors
  • • Iterate and improve based on feedback

The Core Principle: Give Your Agent a Computer

The fundamental insight from Anthropic's approach is simple but powerful: give your AI agent the same tools that humans use to work with computers. This means access to:

  • • File system operations - Read, write, and search files
  • • Command line access - Run bash commands and scripts
  • • Code generation - Write and execute code when needed
  • • External integrations - Connect to APIs and services

This approach transforms Claude from a text generator into a true digital worker that can operate like a human assistant with computer access.

The Agent Feedback Loop

Anthropic identifies a consistent pattern in effective agents: gather context → take action → verify work → repeat.

šŸ”„ The Three-Phase Agent Loop

  1. 1. Gather Context
    • • Search through files and data sources
    • • Understand the current state and requirements
    • • Identify what information is needed
  2. 2. Take Action
    • • Execute tasks using available tools
    • • Generate code, documents, or other outputs
    • • Make decisions based on gathered context
  3. 3. Verify Work
    • • Check outputs against defined rules
    • • Test functionality and accuracy
    • • Iterate and improve based on results

Building a Personal Research Assistant

Let's build a practical example: a personal research assistant that can help you analyze documents, generate summaries, and answer questions about your research materials.

Phase 1: Gathering Context

Our research assistant needs to understand what information is available and what the user is asking for.

šŸ“ Context Gathering Tools

# File system search capabilities
def search_documents(query, file_types=['.pdf', '.txt', '.md']):
    """Search through documents for relevant information"""
    # Use bash commands to search file contents
    # grep -r "query" ./documents --include="*.pdf" --include="*.txt"
    pass

def get_document_summary(file_path):
    """Extract key information from a document"""
    # Read file, extract metadata, identify key topics
    pass

def understand_user_query(query):
    """Parse and understand what the user is asking for"""
    # Break down the request into actionable tasks
    pass

Phase 2: Taking Action

Once we understand the context, our agent can take specific actions to fulfill the user's request.

⚔ Action Tools

# Core action capabilities
def generate_research_summary(topic, sources):
    """Create a comprehensive summary from multiple sources"""
    # Analyze sources, extract key points, synthesize information
    pass

def answer_question(question, context_documents):
    """Answer specific questions based on available documents"""
    # Search relevant sections, provide evidence-based answers
    pass

def create_research_report(topic, findings, format='markdown'):
    """Generate a formatted research report"""
    # Structure findings, add citations, format output
    pass

def update_knowledge_base(new_information):
    """Add new information to the research database"""
    # Process and categorize new information for future use
    pass

Phase 3: Verifying Work

Our agent needs to check its own work to ensure quality and accuracy.

āœ… Verification Tools

# Quality assurance capabilities
def verify_summary_completeness(summary, sources):
    """Check if summary covers all important points from sources"""
    # Compare summary against source material
    pass

def check_fact_accuracy(claims, source_documents):
    """Verify that claims are supported by source material"""
    # Cross-reference claims with original sources
    pass

def validate_report_structure(report):
    """Ensure report follows proper format and structure"""
    # Check formatting, completeness, logical flow
    pass

def test_answer_quality(question, answer, sources):
    """Evaluate if answer adequately addresses the question"""
    # Assess relevance, completeness, and accuracy
    pass

Implementation Strategy

Here's how to structure your research assistant using the Claude Agent SDK:

šŸ—ļø Project Structure

research-assistant/
ā”œā”€ā”€ documents/           # Your research materials
│   ā”œā”€ā”€ papers/
│   ā”œā”€ā”€ notes/
│   └── reports/
ā”œā”€ā”€ tools/              # Agent tools
│   ā”œā”€ā”€ search.py
│   ā”œā”€ā”€ summarize.py
│   ā”œā”€ā”€ verify.py
│   └── report.py
ā”œā”€ā”€ config/             # Configuration
│   ā”œā”€ā”€ agent_config.yaml
│   └── tool_permissions.json
└── outputs/            # Generated reports and summaries
    ā”œā”€ā”€ summaries/
    └── reports/

Key Implementation Tips

šŸ” Context Management

  • • Use file system as your "database"
  • • Implement semantic search for concepts
  • • Create subagents for parallel processing
  • • Use compaction for long conversations

⚔ Action Design

  • • Design tools as primary actions
  • • Use bash for flexible operations
  • • Generate code for complex tasks
  • • Leverage MCPs for integrations

āœ… Verification Methods

  • • Define clear rules for outputs
  • • Use visual feedback when possible
  • • Implement LLM-as-judge for quality
  • • Test with representative examples

🚨 Common Pitfalls

  • • Don't skip verification steps
  • • Avoid overly complex tool designs
  • • Test with real-world scenarios
  • • Monitor for context window limits

Getting Started: Your First Agent

Ready to build your first agent? Here's a step-by-step approach:

šŸš€ 30-Minute Quick Start

  1. 1. Set up your environment (5 min)
    • • Install Claude Agent SDK
    • • Create project directory structure
    • • Set up basic configuration
  2. 2. Create your first tool (10 min)
    • • Build a simple file search function
    • • Test it with sample documents
    • • Add basic error handling
  3. 3. Implement the agent loop (10 min)
    • • Add context gathering capability
    • • Create a simple action tool
    • • Implement basic verification
  4. 4. Test and iterate (5 min)
    • • Run your agent with test queries
    • • Identify areas for improvement
    • • Plan next enhancements

Advanced Capabilities

Once you have the basics working, you can enhance your agent with more sophisticated capabilities:

šŸ”§ Advanced Features

  • • Subagents: Spin up specialized agents for different tasks (search, analysis, formatting)
  • • MCP Integration: Connect to external services like Slack, GitHub, or Google Drive
  • • Visual Feedback: Use screenshots and visual verification for UI-related tasks
  • • Code Generation: Let your agent write and execute code for complex operations
  • • Parallel Processing: Run multiple operations simultaneously for better performance

Real-World Applications

The research assistant is just one example. Here are other agents you could build using the same principles:

šŸ’¼ Business Applications

  • • Finance Agent: Portfolio analysis, investment research
  • • Customer Support: Ticket handling, FAQ generation
  • • Content Creation: Blog posts, social media content
  • • Data Analysis: Report generation, trend analysis

šŸ  Personal Applications

  • • Personal Assistant: Calendar management, travel planning
  • • Learning Agent: Study guides, quiz generation
  • • Health Tracker: Symptom analysis, medication reminders
  • • Home Automation: Smart home control, energy optimization

Key Takeaways

šŸ’” Essential Principles

  • • Give your agent a computer: Access to file systems, command line, and code generation
  • • Follow the three-phase loop: Gather context → Take action → Verify work
  • • Design tools as primary actions: Make them prominent in the agent's context
  • • Implement verification: Rules-based, visual, or LLM-as-judge feedback
  • • Start simple, iterate: Build basic functionality first, then enhance
  • • Test with real scenarios: Use representative examples to validate your agent

Conclusion

The Claude Agent SDK represents a significant step forward in making AI agents practical and useful. By following the three-phase loop and giving your agent access to computer tools, you can build sophisticated assistants that can handle complex, multi-step tasks.

The key is to start simple with a clear use case, implement the basic feedback loop, and then iteratively improve based on real-world testing. Whether you're building a research assistant, a business automation tool, or a personal productivity agent, these principles will guide you toward creating reliable, useful AI agents.

Ready to build your first agent? Start with the research assistant example above, and you'll be amazed at how quickly you can create something genuinely useful.

šŸ“ Source Attribution

This blog post is based on Anthropic's comprehensive guide to building agents with the Claude Agent SDK.

Original source:Building agents with the Claude Agent SDK

This post distills the original content into actionable steps and provides a practical example that developers can implement to get started with agent development.