Sampling

using System.ComponentModel;
using Microsoft.Extensions.AI;
using ModelContextProtocol.Server;

[McpServerToolType]
public class SummaryTools
{
    [McpServerTool(Name = "SummarizeContent"), Description("Summarises arbitrary text using the client's LLM.")]
    public static async Task<string> Summarize(
        IMcpServer server,
        [Description("The text to summarize")] string text,
        CancellationToken cancellationToken)
    {
        ChatMessage[] messages =
        [
            new(ChatRole.User, "Briefly summarize the following content:"),
            new(ChatRole.User, text),
        ];

        var options = new ChatOptions
        {
            MaxOutputTokens = 256,
            Temperature = 0.3f,
        };

        var response = await server.AsSamplingChatClient()
            .GetResponseAsync(messages, options, cancellationToken);

        return $"Summary: {response}";
    }
}

using ModelContextProtocol.Protocol;

CreateMessageResult result = await server.SampleAsync(
    new CreateMessageRequestParams
    {
        Messages =
        [
            new SamplingMessage
            {
                Role = Role.User,
                Content = [new TextContentBlock { Text = "What is 2 + 2?" }]
            }
        ],
        MaxTokens = 100,
        Temperature = 0.0f,
        SystemPrompt = "You are a precise calculator.",
        // ModelPreferences, StopSequences, IncludeContext...
    },
    cancellationToken);

string answer = result.Content
    .OfType<TextContentBlock>()
    .FirstOrDefault()?.Text ?? string.Empty;

ModelPreferences = new ModelPreferences
{
    Hints = [new ModelHint { Name = "claude" }],   // soft preference
    CostPriority = 0.2,        // 0..1
    SpeedPriority = 0.4,
    IntelligencePriority = 0.9,
}

IncludeContext = ContextInclusion.ThisServer   // include this server's prior messages
// or AllServers, or None (default)

if (server.ClientCapabilities?.Sampling is null)
    throw new McpException(
        "This client does not support sampling. " +
        "Configure a model in the host or use a different MCP client.");