MCP Kotlin SDK/org.jetbrains.kotlinx.mcp.server/Server

Server

open class Server(serverInfo: Implementation, options: ServerOptions, var onCloseCallback: () -> Unit? = null) : Protocol<ServerRequest, ServerNotification, ServerResult> (source)

An MCP server on top of a pluggable transport.

This server automatically responds to the initialization flow as initiated by the client. You can register tools, prompts, and resources using addTool, addPrompt, and addResource. The server will then automatically handle listing and retrieval requests from the client.

Parameters

serverInfo

Information about this server implementation (name, version).

options

Configuration options for the server.

onCloseCallback

A callback invoked when the server connection closes.

Constructors

Server

constructor(serverInfo: Implementation, options: ServerOptions, onCloseCallback: () -> Unit? = null)

Properties

clientCapabilities

var clientCapabilities: ClientCapabilities?

The client's reported capabilities after initialization.

clientVersion

var clientVersion: Implementation?

The client's version information after initialization.

fallbackNotificationHandler

var fallbackNotificationHandler: suspend (notification: JSONRPCNotification) -> Unit?

A handler to invoke for any notification types that do not have their own handler installed.

fallbackRequestHandler

var fallbackRequestHandler: suspend (request: JSONRPCRequest, extra: RequestHandlerExtra) -> ServerResult??

A handler to invoke for any request types that do not have their own handler installed.

notificationHandlers

val notificationHandlers: MutableMap<String, suspend (notification: JSONRPCNotification) -> Unit>

onCloseCallback

var onCloseCallback: () -> Unit?

onInitialized

var onInitialized: () -> Unit?

A callback invoked when the server has completed the initialization sequence. After initialization, the server is ready to handle requests.

transport

var transport: Transport?

Functions

addPrompt

fun addPrompt(prompt: Prompt, promptProvider: suspend (GetPromptRequest) -> GetPromptResult)

Registers a single prompt. The prompt can then be retrieved by the client.

fun addPrompt(name: String, description: String? = null, arguments: List<PromptArgument>? = null, promptProvider: suspend (GetPromptRequest) -> GetPromptResult)

Registers a single prompt by constructing a Prompt from given parameters.

addPrompts

fun addPrompts(promptsToAdd: List<RegisteredPrompt>)

Registers multiple prompts at once.

addResource

fun addResource(uri: String, name: String, description: String, mimeType: String = "text/html", readHandler: suspend (ReadResourceRequest) -> ReadResourceResult)

Registers a single resource. The resource content can then be read by the client.

addResources

fun addResources(resourcesToAdd: List<RegisteredResource>)

Registers multiple resources at once.

addTool

fun addTool(name: String, description: String, inputSchema: Tool.Input = Tool.Input(), handler: suspend (CallToolRequest) -> CallToolResult)

Registers a single tool. This tool can then be called by the client.

addTools

fun addTools(toolsToAdd: List<RegisteredTool>)

Registers multiple tools at once.

assertCapabilityForMethod

open override fun assertCapabilityForMethod(method: Method)

Asserts that the client supports the capability required for the given method.

assertRequestHandlerCapability

open override fun assertRequestHandlerCapability(method: Method)

Asserts that the server can handle the specified request method.

suspend fun close()

Closes the connection.

connect

open suspend fun connect(transport: Transport)

Attaches to the given transport, starts it, and starts listening for messages.

createMessage

suspend fun createMessage(params: CreateMessageRequest, options: RequestOptions? = null): CreateMessageResult

Creates a message using the server's sampling capability.

listRoots

suspend fun listRoots(params: JsonObject = EmptyJsonObject, options: RequestOptions? = null): ListRootsResult

Lists the available "roots" from the client's perspective (if supported).

notification

suspend fun notification(notification: ServerNotification)

Emits a notification, which is a one-way message that does not expect a response.

onclose

open override fun onclose()

Called when the server connection is closing. Invokes onCloseCallback if set.

onerror

open fun onerror(error: Throwable)

Callback for when an error occurs.

ping

suspend fun ping(): EmptyRequestResult

Sends a ping request to the client to check connectivity.

removeNotificationHandler

fun removeNotificationHandler(method: Method)

Removes the notification handler for the given method.

removeRequestHandler

fun removeRequestHandler(method: Method)

Removes the request handler for the given method.

request

suspend fun <T : RequestResult> request(request: ServerRequest, options: RequestOptions? = null): T

Sends a request and wait for a response.

sendLoggingMessage

suspend fun sendLoggingMessage(params: LoggingMessageNotification)

Sends a logging message notification to the client.

sendPromptListChanged

suspend fun sendPromptListChanged()

Sends a notification to the client indicating that the list of prompts has changed.

sendResourceListChanged

suspend fun sendResourceListChanged()

Sends a notification to the client indicating that the list of resources has changed.

sendResourceUpdated

suspend fun sendResourceUpdated(params: ResourceUpdatedNotification)

Sends a resource-updated notification to the client, indicating that a specific resource has changed.

sendToolListChanged

suspend fun sendToolListChanged()

Sends a notification to the client indicating that the list of tools has changed.

setNotificationHandler

fun <T : Notification> setNotificationHandler(method: Method, handler: (notification: T) -> Deferred<Unit>)

Registers a handler to invoke when this protocol object receives a notification with the given method.

setRequestHandler

inline fun <T : Request> setRequestHandler(method: Method, noinline block: suspend (T, RequestHandlerExtra) -> ServerResult?)

Registers a handler to invoke when this protocol object receives a request with the given method.