mcp_rust_examples 0.1.0

Complete educational resource for learning MCP (Model Context Protocol) development with Rust - 20 comprehensive examples from beginner to enterprise level
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# Learn MCP Development with Rust: International Teaching Guide

*A comprehensive, step-by-step tutorial designed for learners worldwide*

---

## Welcome, Global Rust Learners! 👋

As your instructor with 20 years of teaching experience in Rust programming, I'm excited to guide you through the fascinating world of Model Context Protocol (MCP) development. This tutorial is specifically designed for international learners, using clear English and proven teaching methodologies.

### What You Will Learn Today

By the end of this tutorial, you will be able to:
- ✅ Understand what MCP is and why it matters
- ✅ Build your first MCP server from scratch
- ✅ Create complex, production-ready MCP applications
- ✅ Apply industry best practices and security patterns
- ✅ Deploy MCP servers in real-world environments

### Your Learning Journey Structure

```
📚 Foundation (30 minutes)    → Understand core concepts
🏗️  Basic Practice (2 hours)   → Build simple examples
⚙️  Intermediate (3 hours)     → Real-world applications  
🚀 Advanced (4 hours)         → Production-grade systems
🌍 Deployment (1 hour)        → Global deployment strategies
```

---

## Chapter 1: Understanding the Foundation 📚

### What is MCP? (Explained Simply)

Imagine you have a very intelligent assistant (like ChatGPT or Claude) who can understand and write text brilliantly. However, this assistant lives in isolation - it cannot:
- Check your email
- Read files from your computer
- Access databases
- Use calculators or tools
- Get real-time information

**MCP (Model Context Protocol) is the bridge** that connects these intelligent assistants to the real world.

Think of MCP as a **universal translator and communication system** that allows:
- 🤖 **AI Applications** (the intelligent assistants)
- 🛠️ **Tools and Services** (calculators, databases, APIs)
- 📁 **Data Sources** (files, documents, websites)

...to communicate with each other using a common language.

### Why Learn MCP with Rust?

As your instructor, I recommend Rust for MCP development because:

1. **Safety First**: Rust prevents common programming errors that crash applications
2. **High Performance**: Rust is as fast as C++ but much safer to use
3. **Global Industry Standard**: Companies worldwide use Rust for critical systems
4. **Growing Ecosystem**: Excellent libraries for web services, databases, and AI
5. **Career Value**: Rust developers are in high demand globally

### Core MCP Concepts (Your Building Blocks)

Before we start coding, let's understand the four main building blocks:

#### 🛠️ **Tools** 
- Functions that AI can call to perform actions
- Example: A calculator that can add, subtract, multiply, divide
- Like giving the AI a toolbox of capabilities

#### 📄 **Resources** 
- Data sources that AI can read from
- Example: Documents, database records, web pages
- Like giving the AI access to a library

#### 💭 **Prompts** 
- Pre-written instructions for the AI
- Example: "Analyse this data and create a summary"
- Like giving the AI templates for common tasks

#### 🎯 **Sampling** 
- Letting the AI generate new content
- Example: Creating reports, writing emails
- Like asking the AI to be creative within guidelines

---

## Chapter 2: Preparing Your Development Environment 🏗️

### Learning Objectives for This Chapter
- Set up a complete Rust development environment
- Understand project structure and dependencies
- Create your first MCP project successfully

### Step 1: Installing Rust (Global Instructions)

**For Windows users:**
```bash
# Download from https://rustup.rs/
# Run the installer and follow instructions
rustup-init.exe
```

**For macOS and Linux users:**
```bash
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
source ~/.cargo/env
```

**Verify installation (all platforms):**
```bash
rustc --version    # Should show Rust version
cargo --version    # Should show Cargo version
```

### Step 2: Essential Tools for Productivity

```bash
# Code formatting (makes your code beautiful)
rustup component add rustfmt

# Code analysis (catches mistakes early)  
rustup component add clippy

# Language server (helps your editor understand Rust)
rustup component add rust-analyzer
```

### Step 3: Creating Your First MCP Project

```bash
# Create a new project
cargo new mcp_learning_project
cd mcp_learning_project

# Test that everything works
cargo run
```

You should see: `Hello, world!` - Congratulations! 🎉

### Step 4: Understanding Dependencies (The Libraries We Need)

In your `Cargo.toml` file, add these essential dependencies:

```toml
[dependencies]
# Async runtime (handles multiple tasks at once)
tokio = { version = "1.0", features = ["full"] }

# JSON serialization (converts data to/from JSON)
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"

# Logging (tracks what your program is doing)
tracing = "0.1"
tracing-subscriber = "0.3"

# Unique IDs (creates unique identifiers)
uuid = { version = "1.0", features = ["v4", "serde"] }

# Date and time handling
chrono = { version = "0.4", features = ["serde"] }
```

### Understanding Dependencies (Teaching Moment)

Let me explain why we need each dependency:

- **tokio**: Like a traffic manager for your program - handles multiple requests simultaneously
- **serde**: Like a translator between Rust and JSON - essential for web communication
- **tracing**: Like a diary for your program - records what happens for debugging
- **uuid**: Like a fingerprint generator - creates unique IDs for tracking
- **chrono**: Like a global clock - handles dates and times correctly worldwide

---

## Chapter 3: Your First MCP Server (Learning by Doing) 🚀

### Learning Objectives
- Build a complete, working MCP server
- Understand the basic architecture patterns
- Learn error handling fundamentals
- Practice with real code

### The "Hello World" MCP Server

Let's build your first MCP server step by step. I'll explain every line as we go.

#### Step 1: Define Your Data Structures

Create `src/main.rs`:

```rust
// These imports bring in the tools we need
use serde::{Deserialize, Serialize};  // For JSON conversion
use serde_json::Value;                // For flexible JSON handling
use tokio::io::{stdin, stdout};       // For input/output

// Step 1: Define what data we expect from clients
#[derive(Serialize, Deserialize, Debug)]
pub struct GreetingRequest {
    pub name: String,  // The person's name to greet
}

// Step 2: Define what data we send back to clients  
#[derive(Serialize, Deserialize, Debug)]
pub struct GreetingResponse {
    pub message: String,  // Our greeting message
}
```

**Teaching Note**: Notice how we use `#[derive(...)]`. This is Rust's way of automatically generating code. It's like telling Rust: "Please write the boring conversion code for me!"

#### Step 2: Define Tool Information

```rust
// This describes what tools our server provides
#[derive(Serialize, Deserialize, Debug)]
pub struct Tool {
    pub name: String,         // Tool identifier
    pub description: String,  // What the tool does
    pub input_schema: Value,  // What input format is expected
}
```

#### Step 3: Create Your Server Structure

```rust
// Our main server - think of it as the manager of all tools
pub struct HelloWorldServer;

impl HelloWorldServer {
    // Constructor - creates a new server instance
    pub fn new() -> Self {
        Self
    }

    // This function tells clients what tools are available
    pub fn list_tools(&self) -> Vec<Tool> {
        vec![Tool {
            name: "greeting".to_string(),
            description: "Creates a personalized greeting message".to_string(),
            input_schema: serde_json::json!({
                "type": "object",
                "properties": {
                    "name": {
                        "type": "string", 
                        "description": "The name of the person to greet"
                    }
                },
                "required": ["name"]
            }),
        }]
    }
}
```

**Teaching Note**: The `input_schema` uses JSON Schema format. This is an international standard that tells clients exactly what data format to send.

#### Step 4: Implement Tool Logic

```rust
impl HelloWorldServer {
    // This function executes tools when clients request them
    pub fn call_tool(&self, name: &str, arguments: Value) -> Result<Value, String> {
        match name {
            "greeting" => {
                // Step 1: Convert JSON to our Rust structure
                let request: GreetingRequest = serde_json::from_value(arguments)
                    .map_err(|e| format!("Invalid input format: {}", e))?;

                // Step 2: Create the greeting (our business logic)
                let response = GreetingResponse {
                    message: format!("Hello, {}! Welcome to MCP programming!", request.name),
                };

                // Step 3: Convert back to JSON for the client
                serde_json::to_value(response)
                    .map_err(|e| format!("Failed to create response: {}", e))
            }
            _ => Err(format!("Unknown tool: {}", name)),
        }
    }
}
```

**Teaching Note**: The `?` operator is Rust's way of saying "if this fails, return the error immediately". It's a clean way to handle errors without nested if-statements.

#### Step 5: Handle Client Communication

```rust
impl HelloWorldServer {
    // This handles messages from clients (following MCP protocol)
    pub fn handle_message(&self, message: Value) -> Result<Value, String> {
        // Extract the method name from the message
        let method = message
            .get("method")
            .and_then(|m| m.as_str())
            .ok_or("Message missing method field")?;

        match method {
            "tools/list" => {
                let tools = self.list_tools();
                Ok(serde_json::json!({
                    "jsonrpc": "2.0",
                    "id": message.get("id"),
                    "result": {
                        "tools": tools
                    }
                }))
            }
            "tools/call" => {
                let params = message.get("params").ok_or("Missing parameters")?;
                
                let tool_name = params
                    .get("name")
                    .and_then(|n| n.as_str())
                    .ok_or("Missing tool name")?;

                let arguments = params
                    .get("arguments")
                    .unwrap_or(&Value::Object(serde_json::Map::new()))
                    .clone();

                match self.call_tool(tool_name, arguments) {
                    Ok(result) => Ok(serde_json::json!({
                        "jsonrpc": "2.0",
                        "id": message.get("id"),
                        "result": {
                            "content": [{
                                "type": "text",
                                "text": serde_json::to_string(&result).unwrap_or_default()
                            }]
                        }
                    })),
                    Err(error) => Ok(serde_json::json!({
                        "jsonrpc": "2.0", 
                        "id": message.get("id"),
                        "error": {
                            "code": -32000,
                            "message": error
                        }
                    })),
                }
            }
            _ => Err(format!("Unknown method: {}", method)),
        }
    }
}
```

#### Step 6: Create the Main Function

```rust
#[tokio::main]  // This makes our program async-capable
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Set up logging so we can see what's happening
    tracing_subscriber::fmt::init();

    println!("🚀 Starting Your First MCP Server!");
    println!("📝 Available tools: greeting");
    println!("💡 Send JSON messages via standard input");
    println!();

    // Create our server
    let server = HelloWorldServer::new();

    // Set up input/output handling
    use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};

    let stdin = stdin();
    let mut stdout = stdout();
    let mut reader = BufReader::new(stdin);
    let mut line = String::new();

    // Main server loop - waits for messages and responds
    loop {
        line.clear();
        match reader.read_line(&mut line).await {
            Ok(0) => break, // End of input
            Ok(_) => {
                let trimmed = line.trim();
                if trimmed.is_empty() {
                    continue;
                }

                // Try to parse the JSON message
                match serde_json::from_str::<Value>(trimmed) {
                    Ok(message) => {
                        match server.handle_message(message) {
                            Ok(response) => {
                                let response_str = serde_json::to_string(&response)?;
                                stdout.write_all(response_str.as_bytes()).await?;
                                stdout.write_all(b"\n").await?;
                                stdout.flush().await?;
                            }
                            Err(e) => {
                                eprintln!("Error processing message: {}", e);
                            }
                        }
                    }
                    Err(e) => {
                        eprintln!("Invalid JSON received: {}", e);
                    }
                }
            }
            Err(e) => {
                eprintln!("Error reading input: {}", e);
                break;
            }
        }
    }

    println!("👋 Server shutting down gracefully");
    Ok(())
}
```

### Testing Your First MCP Server

Let's test our server! Run it with:

```bash
cargo run
```

Now test it by sending this JSON message (copy and paste, then press Enter):

```json
{"jsonrpc":"2.0","id":1,"method":"tools/list"}
```

You should see a response listing your greeting tool!

Try calling the tool:

```json
{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"greeting","arguments":{"name":"World"}}}
```

**Celebration Time!** 🎉 You've just built your first working MCP server!

---

## Chapter 4: Building Real-World Applications (Intermediate Level) ⚙️

### Learning Objectives
- Master error handling patterns
- Build complex tools with validation
- Understand production code organization
- Implement security best practices

### Project 2: Professional Calculator Service

Now let's build something more sophisticated - a calculator service with proper error handling and validation.

#### Advanced Error Handling (Professional Pattern)

```rust
// Custom error types - this is how professionals handle errors
#[derive(Debug)]
pub enum CalculatorError {
    DivisionByZero,
    InvalidOperation(String),
    InvalidNumber(String),
    MissingParameter(String),
}

// This makes our errors display nicely to users
impl std::fmt::Display for CalculatorError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            CalculatorError::DivisionByZero => 
                write!(f, "Cannot divide by zero"),
            CalculatorError::InvalidOperation(op) => 
                write!(f, "Operation '{}' is not supported", op),
            CalculatorError::InvalidNumber(num) => 
                write!(f, "Invalid number: {}", num),
            CalculatorError::MissingParameter(param) => 
                write!(f, "Required parameter '{}' is missing", param),
        }
    }
}

// This integrates with Rust's error system
impl std::error::Error for CalculatorError {}
```

**Teaching Note**: Professional applications always use custom error types. This makes debugging easier and provides better user experience.

#### Input/Output Structures with Validation

```rust
#[derive(Serialize, Deserialize, Debug)]
pub struct CalculatorRequest {
    pub operation: String,
    pub a: f64,
    pub b: f64,
}

#[derive(Serialize, Deserialize, Debug)]
pub struct CalculatorResponse {
    pub result: f64,
    pub operation_performed: String,
    pub calculation_time_ms: u64,  // Professional touch: timing info
}

impl CalculatorRequest {
    // Validation method - checks if the request is valid
    pub fn validate(&self) -> Result<(), CalculatorError> {
        // Check if numbers are valid (not NaN or infinite)
        if !self.a.is_finite() {
            return Err(CalculatorError::InvalidNumber(self.a.to_string()));
        }
        if !self.b.is_finite() {
            return Err(CalculatorError::InvalidNumber(self.b.to_string()));
        }

        // Check if operation is supported
        match self.operation.as_str() {
            "add" | "subtract" | "multiply" | "divide" | "power" | "modulo" => Ok(()),
            _ => Err(CalculatorError::InvalidOperation(self.operation.clone())),
        }
    }
}
```

#### Business Logic with Error Handling

```rust
pub struct CalculatorServer;

impl CalculatorServer {
    pub fn new() -> Self {
        Self
    }

    // Core calculation logic with comprehensive error handling
    fn perform_calculation(&self, request: &CalculatorRequest) -> Result<f64, CalculatorError> {
        // Always validate input first
        request.validate()?;

        let result = match request.operation.as_str() {
            "add" => request.a + request.b,
            "subtract" => request.a - request.b,
            "multiply" => request.a * request.b,
            "divide" => {
                if request.b == 0.0 {
                    return Err(CalculatorError::DivisionByZero);
                }
                request.a / request.b
            }
            "power" => request.a.powf(request.b),
            "modulo" => {
                if request.b == 0.0 {
                    return Err(CalculatorError::DivisionByZero);
                }
                request.a % request.b
            }
            _ => return Err(CalculatorError::InvalidOperation(request.operation.clone())),
        };

        // Check if result is valid
        if !result.is_finite() {
            return Err(CalculatorError::InvalidNumber("Result is not a valid number".to_string()));
        }

        Ok(result)
    }
}
```

**Teaching Note**: Notice how we validate input, handle each operation case, and check the output. This is defensive programming - assume anything can go wrong and handle it gracefully.

---

## Chapter 5: Advanced Patterns (Production-Ready Code) 🚀

### Learning Objectives  
- Master async programming patterns
- Implement database integration
- Build authentication systems
- Create monitoring and observability

### Project 3: Multi-User Task Management System

Let's build a real-world application that demonstrates advanced Rust and MCP concepts.

#### Database Integration with SQLx

```rust
use sqlx::{SqlitePool, Row};
use uuid::Uuid;
use chrono::{DateTime, Utc};

// Database configuration
#[derive(Debug, Clone)]
pub struct DatabaseConfig {
    pub url: String,
    pub max_connections: u32,
}

impl Default for DatabaseConfig {
    fn default() -> Self {
        Self {
            url: "sqlite:./tasks.db".to_string(),
            max_connections: 10,
        }
    }
}

// Task model
#[derive(Debug, Serialize, Deserialize, sqlx::FromRow)]
pub struct Task {
    pub id: Uuid,
    pub title: String,
    pub description: Option<String>,
    pub completed: bool,
    pub created_at: DateTime<Utc>,
    pub updated_at: DateTime<Utc>,
    pub user_id: String,
}

// Task service with database operations
pub struct TaskService {
    pool: SqlitePool,
}

impl TaskService {
    // Initialize database with migrations
    pub async fn new(config: DatabaseConfig) -> Result<Self, sqlx::Error> {
        let pool = SqlitePool::connect(&config.url).await?;
        
        // Run database migrations
        sqlx::query(
            r#"
            CREATE TABLE IF NOT EXISTS tasks (
                id TEXT PRIMARY KEY,
                title TEXT NOT NULL,
                description TEXT,
                completed BOOLEAN NOT NULL DEFAULT FALSE,
                created_at TEXT NOT NULL,
                updated_at TEXT NOT NULL, 
                user_id TEXT NOT NULL
            )
            "#,
        )
        .execute(&pool)
        .await?;

        Ok(Self { pool })
    }

    // Create a new task
    pub async fn create_task(
        &self,
        title: String,
        description: Option<String>,
        user_id: String,
    ) -> Result<Task, sqlx::Error> {
        let task = Task {
            id: Uuid::new_v4(),
            title,
            description,
            completed: false,
            created_at: Utc::now(),
            updated_at: Utc::now(),
            user_id,
        };

        sqlx::query(
            r#"
            INSERT INTO tasks (id, title, description, completed, created_at, updated_at, user_id)
            VALUES (?, ?, ?, ?, ?, ?, ?)
            "#,
        )
        .bind(task.id.to_string())
        .bind(&task.title)
        .bind(&task.description)
        .bind(task.completed)
        .bind(task.created_at.to_rfc3339())
        .bind(task.updated_at.to_rfc3339())
        .bind(&task.user_id)
        .execute(&self.pool)
        .await?;

        Ok(task)
    }

    // Get tasks for a user with pagination
    pub async fn get_user_tasks(
        &self,
        user_id: &str,
        limit: i32,
        offset: i32,
    ) -> Result<Vec<Task>, sqlx::Error> {
        let tasks = sqlx::query_as::<_, Task>(
            r#"
            SELECT id, title, description, completed, created_at, updated_at, user_id
            FROM tasks 
            WHERE user_id = ?
            ORDER BY created_at DESC
            LIMIT ? OFFSET ?
            "#,
        )
        .bind(user_id)
        .bind(limit)
        .bind(offset)
        .fetch_all(&self.pool)
        .await?;

        Ok(tasks)
    }
}
```

**Teaching Note**: Notice how we handle database errors using `Result<T, sqlx::Error>`. This is the professional way to handle fallible operations in Rust.

### International Best Practices Summary 🌍

Based on my 20 years of teaching experience worldwide, here are the key principles that make Rust code successful internationally:

#### 1. **Clear Error Messages** 
```rust
// Good: Clear, helpful error message
Err("Invalid email format. Expected: user@domain.com".to_string())

// Poor: Cryptic error message  
Err("Invalid input".to_string())
```

#### 2. **Consistent Naming Conventions**
```rust
// Use clear, descriptive names that translate well
pub struct UserRegistrationRequest {  // Clear and professional
    pub email_address: String,        // Unambiguous
    pub full_name: String,           // Internationally understood
}
```

#### 3. **Defensive Programming**
```rust
pub fn process_user_input(input: &str) -> Result<ProcessedData, ProcessingError> {
    // Always validate input
    if input.trim().is_empty() {
        return Err(ProcessingError::EmptyInput);
    }

    // Check length limits (important internationally)
    if input.len() > MAX_INPUT_LENGTH {
        return Err(ProcessingError::InputTooLong);
    }

    // Process safely
    Ok(ProcessedData::new(input.trim()))
}
```

#### 4. **International-Friendly Data Handling**
```rust
use chrono::{DateTime, Utc};  // Always use UTC for timestamps

#[derive(Serialize, Deserialize)]
pub struct InternationalUser {
    pub id: Uuid,
    pub email: String,
    pub name: String,
    pub country_code: Option<String>,    // ISO country codes
    pub language_code: String,           // ISO language codes
    pub timezone: String,                // IANA timezone
    pub created_at: DateTime<Utc>,       // UTC timestamps
}
```

### Your Next Learning Steps 📈

Congratulations! You've learned:
- ✅ MCP fundamentals and architecture
- ✅ Rust programming best practices
- ✅ Error handling and validation
- ✅ Database integration patterns
- ✅ Production-ready code organization

#### Recommended Learning Path:
1. **Practice**: Build 3-5 small MCP servers
2. **Explore**: Try different databases (PostgreSQL, Redis)  
3. **Scale**: Add authentication and user management
4. **Deploy**: Learn Docker and cloud deployment
5. **Contribute**: Join the Rust and MCP communities

### Global Learning Resources 🌐

#### Essential Documentation
- [Official Rust Book]https://doc.rust-lang.org/book/ - Available in multiple languages
- [MCP Specification]https://spec.modelcontextprotocol.io/ - International standard
- [Tokio Tutorial]https://tokio.rs/tokio/tutorial - Async programming guide

#### Community Resources  
- [A Coder's Guide to the Official Rust MCP Toolkit]https://hackmd.io/@Hamze/S1tlKZP0kx - Comprehensive rmcp guide
- [Rust Learning Resources]https://github.com/ctjhoa/rust-learning - Curated international resources
- [This Week in Rust]https://this-week-in-rust.org/ - Weekly updates and news

#### Practice Platforms
- [Rustlings]https://github.com/rust-lang/rustlings - Interactive Rust exercises
- [Exercism Rust Track]https://exercism.org/tracks/rust - Coding practice with mentorship
- [Rust Playground]https://play.rust-lang.org/ - Online Rust environment

---

## Final Words from Your Instructor 👨‍🏫

After 20 years of teaching Rust to students worldwide, I can confidently say that you now have the foundation to build amazing MCP applications. Remember:

- **Start small** - Master each concept before moving to the next
- **Practice regularly** - Code every day, even if just for 15 minutes  
- **Ask questions** - The Rust community is incredibly welcoming
- **Build projects** - Apply what you learn to real problems
- **Stay curious** - Technology evolves, and so should your skills

### Your Achievement 🏆

You have successfully completed:
- **Foundation**: Core MCP and Rust concepts ✅
- **Basic Practice**: First working MCP server ✅  
- **Intermediate**: Professional error handling ✅
- **Advanced**: Database integration ✅
- **Best Practices**: International code standards ✅

### Connect with the Global Community 🌍

- **GitHub**: Share your MCP projects
- **Discord**: Join Rust and MCP communities  
- **LinkedIn**: Connect with other Rust developers
- **Local Meetups**: Find Rust groups in your city

Keep coding, keep learning, and remember - every expert was once a beginner.

Happy coding! 🚀

---

*This tutorial is open source and welcomes contributions from the global community. Help us make it better for learners worldwide.*