Plugin System

TJRPCServer is configured through a plugin system based on a fluent interface. Each feature area — MCP configuration, sessions, authentication, JSON serialization — is encapsulated in a separate plugin, registered via .Plugin.Configure<IPluginInterface>.

The general pattern is:

FJRPCServer
  .Plugin.Configure<IPluginA>
    .SetOption1(...)
    .SetOption2(...)
  .ApplyConfig

  .Plugin.Configure<IPluginB>
    ...
  .ApplyConfig;

Each .Plugin.Configure<T> call returns the interface T, exposing the configuration methods for that plugin. When finished, .ApplyConfig returns to the TJRPCServer so the next plugin can be chained.

This chapter covers only the IMCPConfig plugin. Later chapters will address the session management plugin (ISessionConfig), the authentication plugin (IAuthTokenConfig), and the JSON serialization plugin (IJRPCNeonConfig).

The IMCPConfig Plugin

IMCPConfig is the core configuration plugin. It declares the server's identity, its MCP capabilities, and registers the tool and resource classes that implement the MCP API.

Access it with:

uses
  MCPConnect.Configuration.MCP;

The plugin is divided into three sub-sections, each accessed by name and terminated with .BackToMCP:

FJRPCServer
  .Plugin.Configure<IMCPConfig>

    .Server
      // Server identity and capabilities
    .BackToMCP

    .Resources
      // Resource registration
    .BackToMCP

    .Tools
      // Tool registration
    .BackToMCP;

Server Section

The .Server section declares the server's identity, namespace settings, and which MCP capabilities it exposes.

Method	Description
SetName(name)	Server name reported during MCP initialization (default: 'MCPServer')
SetDescription(description)	Server description returned in the MCP initialize response
SetVersion(version)	Server version string (default: '1.0')
SetIconFolder(folder)	Base folder for resolving icon file paths referenced via tags
SetScopeSeparator(separator)	Separator between scope and tool/prompt name (default: '_'). Must be MCP-compliant (a-zA-Z0-9_- only)
SetCapabilities([...])	Declares which MCP capabilities are active: Tools, Resources, Prompts, Tasks, Logging, Completions
SetCapabilities(proc)	Overload accepting a TProc<TServerCapabilities> for fine-grained capability configuration
SetCapabilities(obj)	Overload accepting a TServerCapabilities instance directly (the config takes ownership)
RegisterWriter(class)	Registers a content writer for converting Delphi types to MCP content

.Server
  .SetName('delphi-mcp-server')
  .SetDescription('A Delphi-powered MCP server')
  .SetVersion('2.0.0')
  .SetIconFolder(GetCurrentDir + '\icons')
  .SetScopeSeparator('_')
  .SetCapabilities([Tools, Resources])
  .RegisterWriter(TMCPImageWriter)
  .RegisterWriter(TMCPPictureWriter)
  .RegisterWriter(TMCPStreamWriter)
  .RegisterWriter(TMCPStringListWriter)
.BackToMCP

SetCapabilities controls which capability blocks appear in the MCP initialize response. Only declare capabilities you actually use. If SetCapabilities is never called, MCPConnect infers capabilities from the registered tools, resources, and prompts.

SetScopeSeparator controls how scoped names are built. When a class is annotated with [MCPScope('auth')] and the separator is '_', a tool named login becomes auth_login.

SetIconFolder sets the base directory used to resolve relative icon paths specified via the icon tag on tools, prompts, or resources. If the icon value is already a full URL (contains ://), it is used as-is.

Content writers (see the Content Writers chapter) teach MCPConnect how to serialize specific Delphi types — TStream, TPicture, TStringList, etc. — as MCP content items.

Tools Section

The .Tools section registers the Delphi classes that contain methods decorated with [McpTool].

Method	Description
RegisterClass(class)	Registers a class whose [McpTool] methods are exposed as MCP tools

.Tools
  .RegisterClass(THelpDeskService)
  .RegisterClass(TTestTool)
.BackToMCP

MCPConnect inspects each registered class via RTTI and automatically generates the MCP tool schema from method signatures and [McpParam] attributes. See the Tools chapter for details on annotating tool methods.

Resources Section

The .Resources section registers classes with [McpResource] methods and static files.

Method	Description
SetBasePath(path)	Base directory for resolving relative file paths
RegisterClass(class)	Registers a class whose [McpResource] methods are exposed as MCP resources
RegisterFile(path, name)	Exposes a static file as an MCP resource

.Resources
  .SetBasePath(GetCurrentDir + '\data')
  .RegisterClass(TWeatherResource)
  .RegisterClass(TDeplphiDayApp)
  .RegisterFile('index.md', 'Index')
  .RegisterFile('documentation\mcp\mcpconnect.pdf', 'MCPConnect Introduction')
.BackToMCP

SetBasePath is used as the root for RegisterFile relative paths. See the Resources chapter for details on implementing resource classes.