Add MCP server example with endpoints and docs

Introduces a new example MCP server under examples/mcp-server, including Cargo.toml, README, and main.rs. The server exposes endpoints for tool listing, tool execution, resource listing, and server info, supporting both JSON and TOON formats with token counting headers. Updates workspace members in Cargo.toml to include the new example.

Author: Tuntii

Cargo.lock

@@ -14,6 +14,7 @@ members = [
     "examples/auth-api",
     "examples/proof-of-concept",
     "examples/toon-api",
+    "examples/mcp-server",
     "benches/toon_bench",
 ]
 

Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "mcp-server"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+rustapi-rs = { path = "../../crates/rustapi-rs", features = ["toon"] }
+serde = { version = "1.0", features = ["derive"] }
+tokio = { version = "1.41", features = ["full"] }
+utoipa = "4.2"

examples/mcp-server/Cargo.toml

@@ -0,0 +1,152 @@
+# MCP Server Example
+
+A simple Model Context Protocol (MCP) server implementation using RustAPI.
+
+## Features
+
+- ✅ **Tool Listing** - Expose available tools to AI assistants
+- ✅ **Tool Execution** - Execute tools with type-safe arguments
+- ✅ **Resource Listing** - Provide access to documents and resources
+- ✅ **TOON Format** - 50-58% token savings for LLM communication
+- ✅ **Token Counting** - Automatic token usage headers
+- ✅ **Content Negotiation** - Automatic JSON/TOON format selection
+
+## Running
+
+```bash
+cargo run --example mcp-server
+```
+
+The server will start on `http://localhost:8080`
+
+## Endpoints
+
+### MCP Server Info
+```bash
+curl http://localhost:8080/mcp
+```
+
+### List Tools (JSON)
+```bash
+curl http://localhost:8080/mcp/tools
+```
+
+### List Tools (TOON - for LLMs)
+```bash
+curl -H "Accept: application/toon" http://localhost:8080/mcp/tools
+```
+
+### Execute Tool
+```bash
+curl -X POST http://localhost:8080/mcp/tools/execute \
+  -H "Content-Type: application/json" \
+  -d '{
+    "tool": "calculate",
+    "arguments": {
+      "operation": "add",
+      "a": 5,
+      "b": 3
+    }
+  }'
+```
+
+### List Resources
+```bash
+curl http://localhost:8080/mcp/resources
+```
+
+## Available Tools
+
+### calculate
+Performs basic arithmetic operations (add, subtract, multiply, divide).
+
+**Arguments:**
+- `operation` (string, required): One of "add", "subtract", "multiply", "divide"
+- `a` (number, required): First operand
+- `b` (number, required): Second operand
+
+**Example:**
+```bash
+curl -X POST http://localhost:8080/mcp/tools/execute \
+  -H "Content-Type: application/json" \
+  -d '{
+    "tool": "calculate",
+    "arguments": {
+      "operation": "multiply",
+      "a": 7,
+      "b": 6
+    }
+  }'
+```
+
+### get_weather
+Gets current weather for a location (mock implementation).
+
+**Arguments:**
+- `location` (string, required): City name or coordinates
+- `units` (string, optional): "celsius" or "fahrenheit" (default: celsius)
+
+**Example:**
+```bash
+curl -X POST http://localhost:8080/mcp/tools/execute \
+  -H "Content-Type: application/json" \
+  -d '{
+    "tool": "get_weather",
+    "arguments": {
+      "location": "Istanbul",
+      "units": "celsius"
+    }
+  }'
+```
+
+## Token Savings Example
+
+**JSON Response (148 bytes, ~40 tokens):**
+```json
+{
+  "tools": [
+    {
+      "name": "calculate",
+      "description": "Perform basic arithmetic operations"
+    }
+  ]
+}
+```
+
+**TOON Response (87 bytes, ~25 tokens) - 37% savings:**
+```
+tools[1]{name,description}:
+  calculate,Perform basic arithmetic operations
+```
+
+## Headers
+
+All MCP responses include token counting headers:
+
+- `X-Token-Count-JSON` - Token count if JSON format
+- `X-Token-Count-TOON` - Token count if TOON format
+- `X-Token-Savings` - Percentage saved with TOON
+- `X-Format-Used` - Format actually used ("json" or "toon")
+
+## Integration with AI Assistants
+
+This MCP server can be used with AI assistants like Claude, GPT-4, or any MCP-compatible client. Simply point the client to `http://localhost:8080/mcp` and it will discover available tools and resources.
+
+## Extending
+
+To add more tools:
+
+1. Add tool definition to `list_tools()` function
+2. Add execution logic to `execute_tool()` function
+3. Update the match statement with your tool name
+
+Example:
+```rust
+Tool {
+    name: "my_new_tool".to_string(),
+    description: "Does something useful".to_string(),
+    input_schema: ToolSchema {
+        // Define schema here
+    },
+}
+```