mcp

MCP Plugin for Nimbus

Model Context Protocol (MCP) support for Nimbus, inspired by Laravel's MCP. Enables AI clients (Claude, Cursor, etc.) to interact with your application through tools, resources, and prompts.

Installation

go get github.com/CodeSyncr/nimbus/plugins/mcp

Add the plugin in your bin/server.go:

import (
    "github.com/CodeSyncr/nimbus"
    nimbusmcp "github.com/CodeSyncr/nimbus/plugins/mcp"
)

func main() {
    app := nimbus.New()

    mcpPlugin := nimbusmcp.New()
    mcpPlugin.Web("/mcp/weather", myWeatherServer)
    app.Use(mcpPlugin)

    // ...
}

Note: Use the nimbusmcp alias to avoid conflict with github.com/mark3labs/mcp-go/mcp.

Creating a Server

Create an MCP server with tools, resources, and prompts:

import (
    "context"
    "fmt"

    nimbusmcp "github.com/CodeSyncr/nimbus/plugins/mcp"
    "github.com/mark3labs/mcp-go/mcp"
)

var myWeatherServer = nimbusmcp.NewServer("Weather Server", "1.0.0",
    mcp.WithInstructions("This server provides weather information and forecasts."),
)

func init() {
    // Add a tool
    myWeatherServer.AddTool(
        mcp.NewTool("get_weather",
            mcp.WithDescription("Get the current weather for a location"),
            mcp.WithString("location", mcp.Required(), mcp.Description("City or location name")),
            mcp.WithString("units", mcp.Enum("celsius", "fahrenheit"), mcp.Default("celsius")),
        ),
        handleGetWeather,
    )

    // Add a resource template
    myWeatherServer.AddResource(
        mcp.NewResourceTemplate("weather://forecast/{location}", "Weather Forecast",
            mcp.WithTemplateDescription("Weather forecast for a location"),
            mcp.WithTemplateMIMEType("application/json"),
        ),
        handleWeatherResource,
    )

    // Add a prompt
    myWeatherServer.AddPrompt(
        mcp.Prompt{
            Name:        "describe-weather",
            Description: "Generate a natural-language weather description",
            Arguments: []mcp.PromptArgument{
                {Name: "location", Description: "The location", Required: true},
                {Name: "tone", Description: "Description tone (formal, casual)", Required: false},
            },
        },
        handleDescribeWeatherPrompt,
    )
}

func handleGetWeather(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
    location, _ := req.RequireString("location")
    units := req.GetString("units", "celsius")
    // Fetch weather...
    return mcp.NewToolResultText(fmt.Sprintf("Weather in %s: 72°%s, sunny", location, units)), nil
}

func handleWeatherResource(ctx context.Context, req mcp.ReadResourceRequest) ([]mcp.ResourceContents, error) {
    uri := req.Params.URI // e.g. "weather://forecast/london"
    // Extract template vars from URI, fetch data, return content...
    return []mcp.ResourceContents{{
        URI:       uri,
        MIMEType:  "application/json",
        Text:      `{"temp":72,"conditions":"sunny"}`,
    }}, nil
}

func handleDescribeWeatherPrompt(ctx context.Context, req mcp.GetPromptRequest) (*mcp.GetPromptResult, error) {
    location := req.Params.Arguments["location"]
    tone := req.Params.Arguments["tone"]
    if tone == "" {
        tone = "casual"
    }
    return &mcp.GetPromptResult{
        Messages: []mcp.PromptMessage{
            {Role: mcp.RoleUser, Content: mcp.TextContent{Type: "text", Text: fmt.Sprintf("Describe the weather in %s in a %s tone.", location, tone)}},
        },
    }, nil
}

Tools

Tools let AI clients perform actions. Define a tool with mcp.NewTool and options like WithDescription, WithString, WithNumber, WithRequired, etc.

mcp.NewTool("calculate",
    mcp.WithDescription("Perform basic arithmetic"),
    mcp.WithString("operation", mcp.Required(), mcp.Enum("add", "subtract", "multiply", "divide")),
    mcp.WithNumber("x", mcp.Required()),
    mcp.WithNumber("y", mcp.Required()),
)

Resources

Resources expose data to AI clients. Use NewResource for static URIs or NewResourceTemplate for dynamic URIs with placeholders:

mcp.NewResourceTemplate("docs://readme/{file}", "Documentation",
    mcp.WithTemplateDescription("Project documentation files"),
    mcp.WithTemplateMIMEType("text/markdown"),
)

Prompts

Prompts provide reusable prompt templates:

mcp.Prompt{
    Name:        "code-review",
    Description: "Review code for best practices",
    Arguments: []mcp.PromptArgument{
        {Name: "language", Description: "Programming language", Required: true},
        {Name: "code", Description: "Code to review", Required: true},
    },
}

Transport

The plugin uses Streamable HTTP transport (MCP spec). AI clients connect via HTTP POST (JSON-RPC) and GET (SSE for streaming). Compatible with Cursor, Claude Desktop, and other MCP clients.

Configuration

References

• MCP Specification
• Laravel MCP
• MCP-Go