mcp-vosdroits: Instructions file for GitHub Copilot

---

description: 'Best practices and patterns for building Model Context Protocol (MCP) servers in Go using the official github.com/modelcontextprotocol/go-sdk package.' applyTo: "**/*.go, **/go.mod, **/go.sum"

Go MCP Server Development Guidelines

When building MCP servers in Go, follow these best practices and patterns using the official Go SDK.

Server Setup

Create an MCP server using mcp.NewServer:

import "github.com/modelcontextprotocol/go-sdk/mcp"

server := mcp.NewServer(
    &mcp.Implementation{
        Name:    "my-server",
        Version: "v1.0.0",
    },
    nil, // or provide mcp.Options
)

Adding Tools

Use mcp.AddTool with struct-based input and output for type safety:

• Define input/output structs with JSON schema tags
• Use jsonschema tags to document fields
• Implement handler functions with proper signature
• Return errors for invalid inputs
• Check context cancellation

Adding Resources

Use mcp.AddResource for providing accessible data:

• Define resource URIs and MIME types
• Implement resource read handlers
• Return appropriate content types
• Handle resource not found errors

Adding Prompts

Use mcp.AddPrompt for reusable prompt templates:

• Define prompt arguments
• Return formatted prompt messages
• Use context for cancellation

Transport Configuration

Stdio Transport

For communication over stdin/stdout (most common for desktop integrations):

if err := server.Run(ctx, &mcp.StdioTransport{}); err != nil {
    log.Fatal(err)
}

HTTP Transport

For HTTP-based communication:

transport := &mcp.HTTPTransport{
    Addr: ":8080",
}
if err := server.Run(ctx, transport); err != nil {
    log.Fatal(err)
}

Error Handling

• Always return proper errors from handlers
• Use context for cancellation checking
• Validate inputs before processing
• Wrap errors with context using fmt.Errorf("%w", err)