MCP Resource Types

Register custom resource type handlers to expose files, data, or content from any protocol as MCP resources.

Quick Start

builder.Services
    .AddCoreAIMcpServer()
    .AddCoreAIFtpMcpResources()
    .AddCoreAISftpMcpResources()
    .AddMcpResourceType<MyDatabaseResourceHandler>("database");

Or, using the builder pattern with stores:

builder.Services.AddCrestAppsCore(crestApps => crestApps
    .AddAISuite(ai => ai
        .AddMcpServer(mcpServer => mcpServer
            .AddYesSqlStores()
            .AddFtpResources()
            .AddSftpResources()
        )
    )
);

Problem & Solution

MCP resources represent files, URLs, or data that clients can read. FTP and SFTP handlers are available as optional packages (CrestApps.Core.AI.Ftp and CrestApps.Core.AI.Sftp), and applications often need additional resource types for databases, APIs, blob storage, or custom protocols. Resource type handlers provide a pluggable extension point.

Built-in Resource Types

Type	Handler	Protocol
ftp	FtpResourceTypeHandler	FTP/FTPS
sftp	SftpResourceTypeHandler	SFTP
datasource-figure	DataSourceFigureResourceHandler	Knowledge figures and charts in a File data source

Register them explicitly with AddCoreAIFtpMcpResources(), AddCoreAISftpMcpResources() and AddCoreAIKnowledgeMcpResources().

Knowledge figures

CrestApps.Core.AI.Mcp.Knowledge publishes one template, crestapps://datasource/{dataSourceId}/figure/{figureId} — the same address a search result carries, so a client can read a figure straight out of what a search told it. Listing resources never enumerates the figures in a knowledge base; only the template is published.

A canonical identifier is short and guessable, so the handler establishes that the object belongs to the data source in the address and is actually a figure or chart before it serves any bytes. Anything else is a not-found.

Registration

builder.Services.AddMcpResourceType<MyHandler>("my-type", entry =>
{
    entry.DisplayName = "My Resource Type";
    entry.Description = "Reads resources from my custom source";
});

AddMcpResourceType<THandler>(type, configure?)

Parameter	Description
type	Unique type identifier string
configure	Optional action to set display name and description

Implementing a Resource Type Handler

public sealed class BlobStorageResourceHandler : McpResourceTypeHandlerBase
{
    private readonly BlobServiceClient _blobClient;

    public BlobStorageResourceHandler(BlobServiceClient blobClient)
    {
        _blobClient = blobClient;
    }

    protected override async Task<McpResourceReadResult> GetResultAsync(
        McpResourceReadContext context,
        CancellationToken cancellationToken)
    {
        var containerClient = _blobClient.GetBlobContainerClient(context.ContainerName);
        var blobClient = containerClient.GetBlobClient(context.ResourcePath);

        var download = await blobClient.DownloadContentAsync(cancellationToken);
        var content = download.Value.Content.ToString();

        return new McpResourceReadResult
        {
            Contents = [new TextResourceContents
            {
                Text = content,
                Uri = context.Uri,
                MimeType = "text/plain",
            }],
        };
    }
}

Key Interfaces

IMcpResourceTypeHandler

public interface IMcpResourceTypeHandler
{
    Task<McpResourceReadResult> ReadAsync(
        McpResourceReadContext context,
        CancellationToken cancellationToken = default);
}

McpResourceTypeHandlerBase

A convenience base class — implement GetResultAsync() instead:

protected abstract Task<McpResourceReadResult> GetResultAsync(
    McpResourceReadContext context,
    CancellationToken cancellationToken);