MCP Kotlin SDK/org.jetbrains.kotlinx.mcp.client/Client

Client

open class Client(clientInfo: Implementation, options: ClientOptions = ClientOptions()) : Protocol<ClientRequest, ClientNotification, ClientResult> (source)

An MCP client on top of a pluggable transport.

The client automatically performs the initialization handshake with the server when connect is called. After initialization, getServerCapabilities and getServerVersion provide details about the connected server.

You can extend this class with custom request/notification/result types if needed.

Parameters

clientInfo

Information about the client implementation (name, version).

options

Configuration options for this client.

Constructors

Client

constructor(clientInfo: Implementation, options: ClientOptions = ClientOptions())

Properties

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) -> ClientResult??

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>

transport

var transport: Transport?

Functions

assertCapabilityForMethod

open override fun assertCapabilityForMethod(method: Method)

A method to check if a capability is supported by the remote side, for the given method to be called.

assertRequestHandlerCapability

open override fun assertRequestHandlerCapability(method: Method)

A method to check if a request handler is supported by the local side, for the given method to be handled.

callTool

suspend fun callTool(request: CallToolRequest, compatibility: Boolean = false, options: RequestOptions? = null): CallToolResultBase?

Calls a tool on the server using a CallToolRequest object.

suspend fun callTool(name: String, arguments: Map<String, Any?>, compatibility: Boolean = false, options: RequestOptions? = null): CallToolResultBase?

Calls a tool on the server by name, passing the specified arguments.

suspend fun close()

Closes the connection.

complete

suspend fun complete(params: CompleteRequest, options: RequestOptions? = null): CompleteResult?

Sends a completion request to the server, typically to generate or complete some content.

connect

open suspend override fun connect(transport: Transport)

Connects the client to the given transport, performing the initialization handshake with the server.

getPrompt

suspend fun getPrompt(request: GetPromptRequest, options: RequestOptions? = null): GetPromptResult?

Retrieves a prompt by name from the server.

getServerCapabilities

fun getServerCapabilities(): ServerCapabilities?

Retrieves the server's reported capabilities after the initialization process completes.

getServerVersion

fun getServerVersion(): Implementation?

Retrieves the server's reported version information after initialization.

listPrompts

suspend fun listPrompts(request: ListPromptsRequest = ListPromptsRequest(), options: RequestOptions? = null): ListPromptsResult?

Lists all available prompts from the server.

listResources

suspend fun listResources(request: ListResourcesRequest = ListResourcesRequest(), options: RequestOptions? = null): ListResourcesResult?

Lists all available resources from the server.

listResourceTemplates

suspend fun listResourceTemplates(request: ListResourceTemplatesRequest, options: RequestOptions? = null): ListResourceTemplatesResult?

Lists resource templates available on the server.

listTools

suspend fun listTools(request: ListToolsRequest = ListToolsRequest(), options: RequestOptions? = null): ListToolsResult?

Lists all available tools on the server.

notification

suspend fun notification(notification: ClientNotification)

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

onclose

open fun onclose()

Callback for when the connection is closed for any reason.

onerror

open fun onerror(error: Throwable)

Callback for when an error occurs.

ping

suspend fun ping(options: RequestOptions? = null): EmptyRequestResult

Sends a ping request to the server to check connectivity.

readResource

suspend fun readResource(request: ReadResourceRequest, options: RequestOptions? = null): ReadResourceResult?

Reads a resource from the server by its URI.

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: ClientRequest, options: RequestOptions? = null): T

Sends a request and wait for a response.

sendRootsListChanged

suspend fun sendRootsListChanged()

Notifies the server that the list of roots has changed. Typically used if the client is managing some form of hierarchical structure.

setLoggingLevel

suspend fun setLoggingLevel(level: LoggingLevel, options: RequestOptions? = null): EmptyRequestResult

Sets the logging level on the server.

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) -> ClientResult?)

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

subscribeResource

suspend fun subscribeResource(request: SubscribeRequest, options: RequestOptions? = null): EmptyRequestResult

Subscribes to resource changes on the server.

unsubscribeResource

suspend fun unsubscribeResource(request: UnsubscribeRequest, options: RequestOptions? = null): EmptyRequestResult

Unsubscribes from resource changes on the server.