add ios and wasm targets (#81)

* add wasm and ios targets

* add yarn.lock file to gitignore

* clean up code

* fix typo in method name

* add wasm server example

* update jrelease publishing for klibs

* update gradle-publish workflow to use macos runner

* update README to reflect multiplatform support and clarify server setup for JVM and WASM

* remove the old main file from the kotlin-mcp-server example

* update api dump

* Refactor `build.gradle.kts`

* clean up imports and remove unnecessary charset specification in tests

* add JS target configuration and update API dump

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/client/Client.kt

@@ -1,7 +1,39 @@
 package io.modelcontextprotocol.kotlin.sdk.client
 
-import io.modelcontextprotocol.kotlin.sdk.*
+import io.modelcontextprotocol.kotlin.sdk.CallToolRequest
+import io.modelcontextprotocol.kotlin.sdk.CallToolResult
+import io.modelcontextprotocol.kotlin.sdk.CallToolResultBase
+import io.modelcontextprotocol.kotlin.sdk.ClientCapabilities
+import io.modelcontextprotocol.kotlin.sdk.CompatibilityCallToolResult
+import io.modelcontextprotocol.kotlin.sdk.CompleteRequest
+import io.modelcontextprotocol.kotlin.sdk.CompleteResult
+import io.modelcontextprotocol.kotlin.sdk.EmptyRequestResult
+import io.modelcontextprotocol.kotlin.sdk.GetPromptRequest
+import io.modelcontextprotocol.kotlin.sdk.GetPromptResult
+import io.modelcontextprotocol.kotlin.sdk.Implementation
+import io.modelcontextprotocol.kotlin.sdk.InitializeRequest
+import io.modelcontextprotocol.kotlin.sdk.InitializeResult
+import io.modelcontextprotocol.kotlin.sdk.InitializedNotification
+import io.modelcontextprotocol.kotlin.sdk.LATEST_PROTOCOL_VERSION
+import io.modelcontextprotocol.kotlin.sdk.ListPromptsRequest
+import io.modelcontextprotocol.kotlin.sdk.ListPromptsResult
+import io.modelcontextprotocol.kotlin.sdk.ListResourceTemplatesRequest
+import io.modelcontextprotocol.kotlin.sdk.ListResourceTemplatesResult
+import io.modelcontextprotocol.kotlin.sdk.ListResourcesRequest
+import io.modelcontextprotocol.kotlin.sdk.ListResourcesResult
+import io.modelcontextprotocol.kotlin.sdk.ListToolsRequest
+import io.modelcontextprotocol.kotlin.sdk.ListToolsResult
+import io.modelcontextprotocol.kotlin.sdk.LoggingLevel
 import io.modelcontextprotocol.kotlin.sdk.LoggingMessageNotification.SetLevelRequest
+import io.modelcontextprotocol.kotlin.sdk.Method
+import io.modelcontextprotocol.kotlin.sdk.PingRequest
+import io.modelcontextprotocol.kotlin.sdk.ReadResourceRequest
+import io.modelcontextprotocol.kotlin.sdk.ReadResourceResult
+import io.modelcontextprotocol.kotlin.sdk.RootsListChangedNotification
+import io.modelcontextprotocol.kotlin.sdk.SUPPORTED_PROTOCOL_VERSIONS
+import io.modelcontextprotocol.kotlin.sdk.ServerCapabilities
+import io.modelcontextprotocol.kotlin.sdk.SubscribeRequest
+import io.modelcontextprotocol.kotlin.sdk.UnsubscribeRequest
 import io.modelcontextprotocol.kotlin.sdk.shared.Protocol
 import io.modelcontextprotocol.kotlin.sdk.shared.ProtocolOptions
 import io.modelcontextprotocol.kotlin.sdk.shared.RequestOptions
@@ -27,7 +59,7 @@ public class ClientOptions(
  * 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, [severCapabilities] and [serverVersion] provide details about the connected server.
+ * After initialization, [serverCapabilities] and [serverVersion] provide details about the connected server.
  *
  * You can extend this class with custom request/notification/result types if needed.
  *
@@ -135,9 +167,7 @@ public open class Client(
             Method.Defined.ResourcesUnsubscribe,
                 -> {
                 val resCaps = serverCapabilities?.resources
-                if (resCaps == null) {
-                    throw IllegalStateException("Server does not support resources (required for $method)")
-                }
+                    ?: error("Server does not support resources (required for $method)")
 
                 if (method == Method.Defined.ResourcesSubscribe && resCaps.subscribe != true) {
                     throw IllegalStateException(

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/client/SSEClientTransport.kt

@@ -1,14 +1,29 @@
 package io.modelcontextprotocol.kotlin.sdk.client
 
-import io.ktor.client.*
-import io.ktor.client.plugins.sse.*
-import io.ktor.client.request.*
-import io.ktor.client.statement.*
-import io.ktor.http.*
+import io.ktor.client.HttpClient
+import io.ktor.client.plugins.sse.ClientSSESession
+import io.ktor.client.plugins.sse.sseSession
+import io.ktor.client.request.HttpRequestBuilder
+import io.ktor.client.request.post
+import io.ktor.client.request.setBody
+import io.ktor.client.statement.bodyAsText
+import io.ktor.http.ContentType
+import io.ktor.http.HttpHeaders
+import io.ktor.http.Url
+import io.ktor.http.append
+import io.ktor.http.isSuccess
 import io.modelcontextprotocol.kotlin.sdk.JSONRPCMessage
 import io.modelcontextprotocol.kotlin.sdk.shared.AbstractTransport
 import io.modelcontextprotocol.kotlin.sdk.shared.McpJson
-import kotlinx.coroutines.*
+import kotlinx.coroutines.CompletableDeferred
+import kotlinx.coroutines.CoroutineName
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.cancelAndJoin
+import kotlinx.coroutines.launch
 import kotlinx.serialization.encodeToString
 import kotlin.concurrent.atomics.AtomicBoolean
 import kotlin.concurrent.atomics.ExperimentalAtomicApi
@@ -44,7 +59,7 @@ public class SseClientTransport(
     }
 
     override suspend fun start() {
-        if (!initialized.compareAndSet(false, true)) {
+        if (!initialized.compareAndSet(expectedValue = false, newValue = true)) {
             error(
                 "SSEClientTransport already started! " +
                         "If using Client class, note that connect() calls start() automatically.",

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/client/StdioClientTransport.kt

@@ -2,13 +2,25 @@ package io.modelcontextprotocol.kotlin.sdk.client
 
 import io.github.oshai.kotlinlogging.KotlinLogging
 import io.modelcontextprotocol.kotlin.sdk.JSONRPCMessage
+import io.modelcontextprotocol.kotlin.sdk.internal.IODispatcher
 import io.modelcontextprotocol.kotlin.sdk.shared.AbstractTransport
 import io.modelcontextprotocol.kotlin.sdk.shared.ReadBuffer
 import io.modelcontextprotocol.kotlin.sdk.shared.serializeMessage
-import kotlinx.coroutines.*
+import kotlinx.coroutines.CoroutineName
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.cancelAndJoin
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.channels.consumeEach
-import kotlinx.io.*
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+import kotlinx.io.Buffer
+import kotlinx.io.Sink
+import kotlinx.io.Source
+import kotlinx.io.buffered
+import kotlinx.io.readByteArray
+import kotlinx.io.writeString
 import kotlin.concurrent.atomics.AtomicBoolean
 import kotlin.concurrent.atomics.ExperimentalAtomicApi
 import kotlin.coroutines.CoroutineContext
@@ -28,7 +40,7 @@ public class StdioClientTransport(
     private val output: Sink
 ) : AbstractTransport() {
     private val logger = KotlinLogging.logger {}
-    private val ioCoroutineContext: CoroutineContext = Dispatchers.IO
+    private val ioCoroutineContext: CoroutineContext = IODispatcher
     private val scope by lazy {
         CoroutineScope(ioCoroutineContext + SupervisorJob())
     }
@@ -38,7 +50,7 @@ public class StdioClientTransport(
     private val readBuffer = ReadBuffer()
 
     override suspend fun start() {
-        if (!initialized.compareAndSet(false, true)) {
+        if (!initialized.compareAndSet(expectedValue = false, newValue = true)) {
             error("StdioClientTransport already started!")
         }
 
@@ -100,7 +112,7 @@ public class StdioClientTransport(
     }
 
     override suspend fun close() {
-        if (!initialized.compareAndSet(true, false)) {
+        if (!initialized.compareAndSet(expectedValue = true, newValue = false)) {
             error("Transport is already closed")
         }
         job?.cancelAndJoin()

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/client/WebSocketClientTransport.kt

@@ -1,10 +1,11 @@
 package io.modelcontextprotocol.kotlin.sdk.client
 
-import io.ktor.client.*
-import io.ktor.client.plugins.websocket.*
-import io.ktor.client.request.*
-import io.ktor.http.*
-import io.ktor.websocket.*
+import io.ktor.client.HttpClient
+import io.ktor.client.plugins.websocket.webSocketSession
+import io.ktor.client.request.HttpRequestBuilder
+import io.ktor.client.request.header
+import io.ktor.http.HttpHeaders
+import io.ktor.websocket.WebSocketSession
 import io.modelcontextprotocol.kotlin.sdk.shared.MCP_SUBPROTOCOL
 import io.modelcontextprotocol.kotlin.sdk.shared.WebSocketMcpTransport
 import kotlin.properties.Delegates

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/internal/utils.kt

@@ -0,0 +1,5 @@
+package io.modelcontextprotocol.kotlin.sdk.internal
+
+import kotlinx.coroutines.CoroutineDispatcher
+
+internal expect val IODispatcher: CoroutineDispatcher

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/KtorServer.kt

@@ -1,12 +1,19 @@
 package io.modelcontextprotocol.kotlin.sdk.server
 
 import io.github.oshai.kotlinlogging.KotlinLogging
-import io.ktor.http.*
-import io.ktor.server.application.*
-import io.ktor.server.response.*
-import io.ktor.server.routing.*
-import io.ktor.server.sse.*
-import io.ktor.util.collections.*
+import io.ktor.http.HttpStatusCode
+import io.ktor.server.application.Application
+import io.ktor.server.application.install
+import io.ktor.server.response.respond
+import io.ktor.server.routing.Routing
+import io.ktor.server.routing.RoutingContext
+import io.ktor.server.routing.post
+import io.ktor.server.routing.route
+import io.ktor.server.routing.routing
+import io.ktor.server.sse.SSE
+import io.ktor.server.sse.ServerSSESession
+import io.ktor.server.sse.sse
+import io.ktor.util.collections.ConcurrentMap
 import io.ktor.utils.io.KtorDsl
 
 private val logger = KotlinLogging.logger {}

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/SSEServerTransport.kt

@@ -1,10 +1,13 @@
 package io.modelcontextprotocol.kotlin.sdk.server
 
-import io.ktor.http.*
-import io.ktor.server.application.*
-import io.ktor.server.request.*
-import io.ktor.server.response.*
-import io.ktor.server.sse.*
+import io.ktor.http.ContentType
+import io.ktor.http.HttpStatusCode
+import io.ktor.http.encodeURLPath
+import io.ktor.server.application.ApplicationCall
+import io.ktor.server.request.contentType
+import io.ktor.server.request.receiveText
+import io.ktor.server.response.respondText
+import io.ktor.server.sse.ServerSSESession
 import io.modelcontextprotocol.kotlin.sdk.JSONRPCMessage
 import io.modelcontextprotocol.kotlin.sdk.shared.AbstractTransport
 import io.modelcontextprotocol.kotlin.sdk.shared.McpJson
@@ -41,8 +44,8 @@ public class SseServerTransport(
      * This should be called when a GET request is made to establish the SSE stream.
      */
     override suspend fun start() {
-        if (!initialized.compareAndSet(false, true)) {
-            throw error("SSEServerTransport already started! If using Server class, note that connect() calls start() automatically.")
+        if (!initialized.compareAndSet(expectedValue = false, newValue = true)) {
+            error("SSEServerTransport already started! If using Server class, note that connect() calls start() automatically.")
         }
 
         // Send the endpoint event
@@ -114,7 +117,7 @@ public class SseServerTransport(
 
     override suspend fun send(message: JSONRPCMessage) {
         if (!initialized.load()) {
-            throw error("Not connected")
+            error("Not connected")
         }
 
         session.send(

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/Server.kt

@@ -1,7 +1,45 @@
 package io.modelcontextprotocol.kotlin.sdk.server
 
 import io.github.oshai.kotlinlogging.KotlinLogging
-import io.modelcontextprotocol.kotlin.sdk.*
+import io.modelcontextprotocol.kotlin.sdk.CallToolRequest
+import io.modelcontextprotocol.kotlin.sdk.CallToolResult
+import io.modelcontextprotocol.kotlin.sdk.ClientCapabilities
+import io.modelcontextprotocol.kotlin.sdk.CreateMessageRequest
+import io.modelcontextprotocol.kotlin.sdk.CreateMessageResult
+import io.modelcontextprotocol.kotlin.sdk.EmptyJsonObject
+import io.modelcontextprotocol.kotlin.sdk.EmptyRequestResult
+import io.modelcontextprotocol.kotlin.sdk.GetPromptRequest
+import io.modelcontextprotocol.kotlin.sdk.GetPromptResult
+import io.modelcontextprotocol.kotlin.sdk.Implementation
+import io.modelcontextprotocol.kotlin.sdk.InitializeRequest
+import io.modelcontextprotocol.kotlin.sdk.InitializeResult
+import io.modelcontextprotocol.kotlin.sdk.InitializedNotification
+import io.modelcontextprotocol.kotlin.sdk.LATEST_PROTOCOL_VERSION
+import io.modelcontextprotocol.kotlin.sdk.ListPromptsRequest
+import io.modelcontextprotocol.kotlin.sdk.ListPromptsResult
+import io.modelcontextprotocol.kotlin.sdk.ListResourceTemplatesRequest
+import io.modelcontextprotocol.kotlin.sdk.ListResourceTemplatesResult
+import io.modelcontextprotocol.kotlin.sdk.ListResourcesRequest
+import io.modelcontextprotocol.kotlin.sdk.ListResourcesResult
+import io.modelcontextprotocol.kotlin.sdk.ListRootsRequest
+import io.modelcontextprotocol.kotlin.sdk.ListRootsResult
+import io.modelcontextprotocol.kotlin.sdk.ListToolsRequest
+import io.modelcontextprotocol.kotlin.sdk.ListToolsResult
+import io.modelcontextprotocol.kotlin.sdk.LoggingMessageNotification
+import io.modelcontextprotocol.kotlin.sdk.Method
+import io.modelcontextprotocol.kotlin.sdk.PingRequest
+import io.modelcontextprotocol.kotlin.sdk.Prompt
+import io.modelcontextprotocol.kotlin.sdk.PromptArgument
+import io.modelcontextprotocol.kotlin.sdk.PromptListChangedNotification
+import io.modelcontextprotocol.kotlin.sdk.ReadResourceRequest
+import io.modelcontextprotocol.kotlin.sdk.ReadResourceResult
+import io.modelcontextprotocol.kotlin.sdk.Resource
+import io.modelcontextprotocol.kotlin.sdk.ResourceListChangedNotification
+import io.modelcontextprotocol.kotlin.sdk.ResourceUpdatedNotification
+import io.modelcontextprotocol.kotlin.sdk.SUPPORTED_PROTOCOL_VERSIONS
+import io.modelcontextprotocol.kotlin.sdk.ServerCapabilities
+import io.modelcontextprotocol.kotlin.sdk.Tool
+import io.modelcontextprotocol.kotlin.sdk.ToolListChangedNotification
 import io.modelcontextprotocol.kotlin.sdk.shared.Protocol
 import io.modelcontextprotocol.kotlin.sdk.shared.ProtocolOptions
 import io.modelcontextprotocol.kotlin.sdk.shared.RequestOptions
@@ -105,7 +143,7 @@ public open class Server(
     /**
      * Registers a callback to be invoked when the server has completed initialization.
      */
-    public fun onInitalized(block: () -> Unit) {
+    public fun onInitialized(block: () -> Unit) {
         val old = _onInitialized
         _onInitialized = {
             old()
@@ -133,7 +171,7 @@ public open class Server(
     }
 
     /**
-     * Registers a single tool. This tool can then be called by the client.
+     * Registers a single tool. The client can then call this tool.
      *
      * @param name The name of the tool.
      * @param description A human-readable description of what the tool does.
@@ -228,7 +266,7 @@ public open class Server(
     }
 
     /**
-     * Registers a single prompt. The prompt can then be retrieved by the client.
+     * Registers a single prompt. The client can then retrieve the prompt.
      *
      * @param prompt A [Prompt] object describing the prompt.
      * @param promptProvider A suspend function that returns the prompt content when requested by the client.
@@ -335,7 +373,7 @@ public open class Server(
     }
 
     /**
-     * Registers a single resource. The resource content can then be read by the client.
+     * Registers a single resource. The client can then read the resource content.
      *
      * @param uri The URI of the resource.
      * @param name A human-readable name for the resource.

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/StdioServerTransport.kt

@@ -2,12 +2,25 @@ package io.modelcontextprotocol.kotlin.sdk.server
 
 import io.github.oshai.kotlinlogging.KotlinLogging
 import io.modelcontextprotocol.kotlin.sdk.JSONRPCMessage
+import io.modelcontextprotocol.kotlin.sdk.internal.IODispatcher
 import io.modelcontextprotocol.kotlin.sdk.shared.AbstractTransport
 import io.modelcontextprotocol.kotlin.sdk.shared.ReadBuffer
 import io.modelcontextprotocol.kotlin.sdk.shared.serializeMessage
-import kotlinx.coroutines.*
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.NonCancellable
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.cancelAndJoin
 import kotlinx.coroutines.channels.Channel
-import kotlinx.io.*
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import kotlinx.io.Buffer
+import kotlinx.io.Sink
+import kotlinx.io.Source
+import kotlinx.io.buffered
+import kotlinx.io.readByteArray
+import kotlinx.io.writeString
 import kotlin.concurrent.atomics.AtomicBoolean
 import kotlin.concurrent.atomics.ExperimentalAtomicApi
 import kotlin.coroutines.CoroutineContext
@@ -29,7 +42,7 @@ public class StdioServerTransport(
     private var readingJob: Job? = null
     private var sendingJob: Job? = null
 
-    private val coroutineContext: CoroutineContext = Dispatchers.IO + SupervisorJob()
+    private val coroutineContext: CoroutineContext = IODispatcher + SupervisorJob()
     private val scope = CoroutineScope(coroutineContext)
     private val readChannel = Channel<ByteArray>(Channel.UNLIMITED)
     private val writeChannel = Channel<JSONRPCMessage>(Channel.UNLIMITED)
@@ -113,15 +126,26 @@ public class StdioServerTransport(
     override suspend fun close() {
         if (!initialized.compareAndSet(expectedValue = true, newValue = false)) return
 
-        // Cancel reading job and close channel
-        readingJob?.cancel() // ToDO("was cancel and join")
-        sendingJob?.cancel()
+        withContext(NonCancellable) {
+            writeChannel.close()
+            sendingJob?.cancelAndJoin()
 
-        readChannel.close()
-        writeChannel.close()
-        readBuffer.clear()
+            runCatching {
+                inputStream.close()
+            }.onFailure { logger.warn(it) { "Failed to close stdin" } }
 
-        _onClose.invoke()
+            readingJob?.cancel()
+
+            readChannel.close()
+            readBuffer.clear()
+
+            runCatching {
+                outputWriter.flush()
+                outputWriter.close()
+            }.onFailure { logger.warn(it) { "Failed to close stdout" } }
+
+            _onClose.invoke()
+        }
     }
 
     override suspend fun send(message: JSONRPCMessage) {

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/WebSocketMcpKtorServerExtensions.kt

@@ -1,7 +1,8 @@
 package io.modelcontextprotocol.kotlin.sdk.server
 
-import io.ktor.server.routing.*
-import io.ktor.server.websocket.*
+import io.ktor.server.routing.Route
+import io.ktor.server.websocket.WebSocketServerSession
+import io.ktor.server.websocket.webSocket
 import io.modelcontextprotocol.kotlin.sdk.Implementation
 import io.modelcontextprotocol.kotlin.sdk.LIB_VERSION
 import io.modelcontextprotocol.kotlin.sdk.ServerCapabilities

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/WebSocketMcpServerTransport.kt

@@ -1,7 +1,7 @@
 package io.modelcontextprotocol.kotlin.sdk.server
 
-import io.ktor.http.*
-import io.ktor.server.websocket.*
+import io.ktor.http.HttpHeaders
+import io.ktor.server.websocket.WebSocketServerSession
 import io.modelcontextprotocol.kotlin.sdk.shared.MCP_SUBPROTOCOL
 import io.modelcontextprotocol.kotlin.sdk.shared.WebSocketMcpTransport
 

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/Protocol.kt

@@ -1,14 +1,35 @@
 package io.modelcontextprotocol.kotlin.sdk.shared
 
 import io.github.oshai.kotlinlogging.KotlinLogging
-import io.modelcontextprotocol.kotlin.sdk.*
+import io.modelcontextprotocol.kotlin.sdk.CancelledNotification
+import io.modelcontextprotocol.kotlin.sdk.EmptyRequestResult
+import io.modelcontextprotocol.kotlin.sdk.ErrorCode
+import io.modelcontextprotocol.kotlin.sdk.JSONRPCError
+import io.modelcontextprotocol.kotlin.sdk.JSONRPCNotification
+import io.modelcontextprotocol.kotlin.sdk.JSONRPCRequest
+import io.modelcontextprotocol.kotlin.sdk.JSONRPCResponse
+import io.modelcontextprotocol.kotlin.sdk.McpError
+import io.modelcontextprotocol.kotlin.sdk.Method
+import io.modelcontextprotocol.kotlin.sdk.Notification
+import io.modelcontextprotocol.kotlin.sdk.PingRequest
+import io.modelcontextprotocol.kotlin.sdk.Progress
+import io.modelcontextprotocol.kotlin.sdk.ProgressNotification
+import io.modelcontextprotocol.kotlin.sdk.Request
+import io.modelcontextprotocol.kotlin.sdk.RequestId
+import io.modelcontextprotocol.kotlin.sdk.RequestResult
+import io.modelcontextprotocol.kotlin.sdk.fromJSON
+import io.modelcontextprotocol.kotlin.sdk.toJSON
 import kotlinx.coroutines.CompletableDeferred
 import kotlinx.coroutines.Deferred
 import kotlinx.coroutines.TimeoutCancellationException
 import kotlinx.coroutines.withTimeout
 import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.encodeToString
-import kotlinx.serialization.json.*
+import kotlinx.serialization.json.ClassDiscriminatorMode
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.JsonObject
+import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.json.encodeToJsonElement
 import kotlinx.serialization.serializer
 import kotlin.reflect.KType
 import kotlin.reflect.typeOf
@@ -47,7 +68,8 @@ public open class ProtocolOptions(
      * considered a logic error to mis-specify those.
      *
      * Currently, this defaults to false, for backwards compatibility with SDK versions
-     * that did not advertise capabilities correctly. In future, this will default to true.
+     * that did not advertise capabilities correctly.
+     * In the future, this will default to true.
      */
     public var enforceStrictCapabilities: Boolean = false,
 
@@ -118,7 +140,8 @@ public abstract class Protocol(
     /**
      * Callback for when an error occurs.
      *
-     * Note that errors are not necessarily fatal they are used for reporting any kind of exceptional condition out of band.
+     * Note that errors are not necessarily fatal they are used
+     * for reporting any kind of exceptional condition out of a band.
      */
     public open fun onError(error: Throwable) {}
 

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/ReadBuffer.kt

@@ -1,6 +1,6 @@
 package io.modelcontextprotocol.kotlin.sdk.shared
 
-import io.ktor.utils.io.core.*
+import io.ktor.utils.io.core.writeFully
 import io.modelcontextprotocol.kotlin.sdk.JSONRPCMessage
 import kotlinx.io.Buffer
 import kotlinx.io.indexOf

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/Transport.kt

@@ -4,7 +4,7 @@ import io.modelcontextprotocol.kotlin.sdk.JSONRPCMessage
 import kotlinx.coroutines.CompletableDeferred
 
 /**
- * Describes the minimal contract for a MCP transport that a client or server can communicate over.
+ * Describes the minimal contract for MCP transport that a client or server can communicate over.
  */
 public interface Transport {
     /**
@@ -38,7 +38,7 @@ public interface Transport {
      * Callback for when an error occurs.
      *
      * Note that errors are not necessarily fatal; they are used for reporting any kind of
-     * exceptional condition out of band.
+     * exceptional condition out of a band.
      */
     public fun onError(block: (Throwable) -> Unit)
 

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/WebSocketMcpTransport.kt

@@ -1,9 +1,17 @@
 package io.modelcontextprotocol.kotlin.sdk.shared
 
-import io.ktor.websocket.*
+import io.ktor.websocket.Frame
+import io.ktor.websocket.WebSocketSession
+import io.ktor.websocket.close
+import io.ktor.websocket.readText
 import io.modelcontextprotocol.kotlin.sdk.JSONRPCMessage
-import kotlinx.coroutines.*
+import kotlinx.coroutines.CoroutineName
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.InternalCoroutinesApi
+import kotlinx.coroutines.SupervisorJob
 import kotlinx.coroutines.channels.ClosedReceiveChannelException
+import kotlinx.coroutines.job
+import kotlinx.coroutines.launch
 import kotlinx.serialization.encodeToString
 import kotlin.concurrent.atomics.AtomicBoolean
 import kotlin.concurrent.atomics.ExperimentalAtomicApi
@@ -21,6 +29,7 @@ public abstract class WebSocketMcpTransport : AbstractTransport() {
     }
 
     private val initialized: AtomicBoolean = AtomicBoolean(false)
+
     /**
      * The WebSocket session used for communication.
      */
@@ -32,7 +41,7 @@ public abstract class WebSocketMcpTransport : AbstractTransport() {
     protected abstract suspend fun initializeSession()
 
     override suspend fun start() {
-        if (!initialized.compareAndSet(false, true)) {
+        if (!initialized.compareAndSet(expectedValue = false, newValue = true)) {
             error(
                 "WebSocketClientTransport already started! " +
                         "If using Client class, note that connect() calls start() automatically.",

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types.kt

@@ -13,6 +13,7 @@ import kotlinx.serialization.json.encodeToJsonElement
 import kotlin.concurrent.atomics.AtomicLong
 import kotlin.concurrent.atomics.ExperimentalAtomicApi
 import kotlin.concurrent.atomics.incrementAndFetch
+import kotlin.jvm.JvmInline
 
 public const val LATEST_PROTOCOL_VERSION: String = "2024-11-05"
 
@@ -184,7 +185,7 @@ internal fun JSONRPCNotification.fromJSON(): Notification {
 public sealed interface RequestResult : WithMeta
 
 /**
- * An empty result for a request, containing optional metadata.
+ * An empty result for a request containing optional metadata.
  *
  * @param _meta Additional metadata for the response. Defaults to an empty JSON object.
  */
@@ -493,7 +494,8 @@ public class InitializedNotification : ClientNotification {
 
 /* Ping */
 /**
- * A ping, issued by either the server or the client, to check that the other party is still alive. The receiver must promptly respond, or else may be disconnected.
+ * A ping, issued by either the server or the client, to check that the other party is still alive.
+ * The receiver must promptly respond, or else it may be disconnected.
  */
 @Serializable
 public class PingRequest : ServerRequest, ClientRequest {
@@ -1492,6 +1494,7 @@ public class RootsListChangedNotification : ClientNotification {
  * @property message The error message.
  * @property data Additional error data as a JSON object.
  */
-public class McpError(public val code: Int, message: String, public val data: JsonObject = EmptyJsonObject) : Exception() {
+public class McpError(public val code: Int, message: String, public val data: JsonObject = EmptyJsonObject) :
+    Exception() {
     override val message: String = "MCP error ${code}: $message"
 }

src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/types.util.kt

@@ -10,7 +10,16 @@ import kotlinx.serialization.descriptors.SerialDescriptor
 import kotlinx.serialization.descriptors.buildClassSerialDescriptor
 import kotlinx.serialization.encoding.Decoder
 import kotlinx.serialization.encoding.Encoder
-import kotlinx.serialization.json.*
+import kotlinx.serialization.json.JsonContentPolymorphicSerializer
+import kotlinx.serialization.json.JsonDecoder
+import kotlinx.serialization.json.JsonElement
+import kotlinx.serialization.json.JsonEncoder
+import kotlinx.serialization.json.JsonObject
+import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.json.jsonObject
+import kotlinx.serialization.json.jsonPrimitive
+import kotlinx.serialization.json.long
+import kotlinx.serialization.json.longOrNull
 
 private val logger = KotlinLogging.logger {}
 
@@ -285,6 +294,7 @@ public class RequestIdSerializer : KSerializer<RequestId> {
                 element.longOrNull != null -> RequestId.NumberId(element.long)
                 else -> error("Invalid RequestId type")
             }
+
             else -> error("Invalid RequestId format")
         }
     }

src/commonTest/kotlin/io/modelcontextprotocol/kotlin/sdk/InMemoryTransport.kt

@@ -0,0 +1,47 @@
+package io.modelcontextprotocol.kotlin.sdk
+
+import io.modelcontextprotocol.kotlin.sdk.shared.AbstractTransport
+
+/**
+ * In-memory transport for creating clients and servers that talk to each other within the same process.
+ */
+class InMemoryTransport : AbstractTransport() {
+    private var otherTransport: InMemoryTransport? = null
+    private val messageQueue: MutableList<JSONRPCMessage> = mutableListOf()
+
+    /**
+     * Creates a pair of linked in-memory transports that can communicate with each other.
+     * One should be passed to a Client and one to a Server.
+     */
+    companion object {
+        fun createLinkedPair(): Pair<InMemoryTransport, InMemoryTransport> {
+            val clientTransport = InMemoryTransport()
+            val serverTransport = InMemoryTransport()
+            clientTransport.otherTransport = serverTransport
+            serverTransport.otherTransport = clientTransport
+            return Pair(clientTransport, serverTransport)
+        }
+    }
+
+    override suspend fun start() {
+        // Process any messages that were queued before start was called
+        while (messageQueue.isNotEmpty()) {
+            messageQueue.removeFirstOrNull()?.let { message ->
+                _onMessage.invoke(message) // todo?
+            }
+        }
+    }
+
+    override suspend fun close() {
+        val other = otherTransport
+        otherTransport = null
+        other?.close()
+        _onClose.invoke()
+    }
+
+    override suspend fun send(message: JSONRPCMessage) {
+        val other = otherTransport ?: throw IllegalStateException("Not connected")
+
+        other._onMessage.invoke(message)
+    }
+}

src/commonTest/kotlin/io/modelcontextprotocol/kotlin/sdk/ToolSerializationTest.kt

@@ -0,0 +1,65 @@
+package io.modelcontextprotocol.kotlin.sdk
+
+import io.kotest.assertions.json.shouldEqualJson
+import io.modelcontextprotocol.kotlin.sdk.shared.McpJson
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.JsonPrimitive
+import kotlinx.serialization.json.buildJsonObject
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class ToolSerializationTest {
+
+    // see https://docs.anthropic.com/en/docs/build-with-claude/tool-use
+    /* language=json */
+    private val getWeatherToolJson = """
+        {
+          "name": "get_weather",
+          "description": "Get the current weather in a given location",
+          "inputSchema": {
+            "type": "object",
+            "properties": {
+              "location": {
+                "type": "string",
+                "description": "The city and state, e.g. San Francisco, CA"
+              }
+            },
+            "required": ["location"]
+          }
+        }
+    """.trimIndent()
+
+    val getWeatherTool = Tool(
+        name = "get_weather",
+        description = "Get the current weather in a given location",
+        inputSchema = Tool.Input(
+            properties = buildJsonObject {
+                put("location", buildJsonObject {
+                    put("type", JsonPrimitive("string"))
+                    put("description", JsonPrimitive("The city and state, e.g. San Francisco, CA"))
+                })
+            },
+            required = listOf("location")
+        )
+    )
+
+    @Test
+    fun `should serialize get_weather tool`() {
+        McpJson.encodeToString(getWeatherTool) shouldEqualJson getWeatherToolJson
+    }
+
+    @Test
+    fun `should deserialize get_weather tool`() {
+        val tool = McpJson.decodeFromString<Tool>(getWeatherToolJson)
+        assertEquals(expected = getWeatherTool, actual = tool)
+    }
+
+    @Test
+    fun `should always serialize default value`() {
+        val json = Json(from = McpJson) {
+            encodeDefaults = false
+        }
+        json.encodeToString(getWeatherTool) shouldEqualJson getWeatherToolJson
+    }
+}

src/commonTest/kotlin/io/modelcontextprotocol/kotlin/sdk/client/BaseTransportTest.kt

@@ -0,0 +1,62 @@
+package io.modelcontextprotocol.kotlin.sdk.client
+
+import io.modelcontextprotocol.kotlin.sdk.InitializedNotification
+import io.modelcontextprotocol.kotlin.sdk.JSONRPCMessage
+import io.modelcontextprotocol.kotlin.sdk.PingRequest
+import io.modelcontextprotocol.kotlin.sdk.shared.Transport
+import io.modelcontextprotocol.kotlin.sdk.toJSON
+import kotlinx.coroutines.CompletableDeferred
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+import kotlin.test.fail
+
+abstract class BaseTransportTest {
+    protected suspend fun testClientOpenClose(client: Transport) {
+        client.onError { error ->
+            fail("Unexpected error: $error")
+        }
+
+        var didClose = false
+        client.onClose { didClose = true }
+
+        client.start()
+        assertFalse(didClose, "Transport should not be closed immediately after start")
+
+        client.close()
+        assertTrue(didClose, "Transport should be closed after close() call")
+    }
+
+    protected suspend fun testClientRead(client: Transport) {
+        client.onError { error ->
+            error.printStackTrace()
+            fail("Unexpected error: $error")
+        }
+
+        val messages = listOf<JSONRPCMessage>(
+            PingRequest().toJSON(), InitializedNotification().toJSON()
+        )
+
+        val readMessages = mutableListOf<JSONRPCMessage>()
+        val finished = CompletableDeferred<Unit>()
+
+        client.onMessage { message ->
+            readMessages.add(message)
+            if (message == messages.last()) {
+                finished.complete(Unit)
+            }
+        }
+
+        client.start()
+
+        for (message in messages) {
+            client.send(message)
+        }
+
+        finished.await()
+
+        assertEquals(messages, readMessages, "Assert messages received")
+
+        client.close()
+    }
+}