Merge branch 'main' into devcrocod/document-public-api

Author: kpavlov

.github/workflows/build.yml

@@ -34,7 +34,7 @@ jobs:
         include:
           - os: ubuntu-latest
             job-name: "Linux Tests"
-            gradle-tasks: "build"
+            gradle-tasks: "ktlintCheck build"
             max-workers: 3
 
           - os: macos-latest

README.md

@@ -19,34 +19,34 @@ standardized protocol interface.
 
 * [Overview](#overview)
 * [Installation](#installation)
-    * [Artifacts](#artifacts)
-    * [Gradle setup (JVM)](#gradle-setup-jvm)
-    * [Multiplatform](#multiplatform)
-    * [Ktor dependencies](#ktor-dependencies)
+  * [Artifacts](#artifacts)
+  * [Gradle setup (JVM)](#gradle-setup-jvm)
+  * [Multiplatform](#multiplatform)
+  * [Ktor dependencies](#ktor-dependencies)
 * [Quickstart](#quickstart)
-    * [Creating a Client](#creating-a-client)
-    * [Creating a Server](#creating-a-server)
+  * [Creating a Client](#creating-a-client)
+  * [Creating a Server](#creating-a-server)
 * [Core Concepts](#core-concepts)
-    * [MCP Primitives](#mcp-primitives)
-    * [Capabilities](#capabilities)
-        * [Server Capabilities](#server-capabilities)
-        * [Client Capabilities](#client-capabilities)
-    * [Server Features](#server-features)
-        * [Prompts](#prompts)
-        * [Resources](#resources)
-        * [Tools](#tools)
-        * [Completion](#completion)
-        * [Logging](#logging)
-        * [Pagination](#pagination)
-    * [Client Features](#client-features)
-        * [Roots](#roots)
-        * [Sampling](#sampling)
+  * [MCP Primitives](#mcp-primitives)
+  * [Capabilities](#capabilities)
+    * [Server Capabilities](#server-capabilities)
+    * [Client Capabilities](#client-capabilities)
+  * [Server Features](#server-features)
+    * [Prompts](#prompts)
+    * [Resources](#resources)
+    * [Tools](#tools)
+    * [Completion](#completion)
+    * [Logging](#logging)
+    * [Pagination](#pagination)
+  * [Client Features](#client-features)
+    * [Roots](#roots)
+    * [Sampling](#sampling)
 * [Transports](#transports)
-    * [STDIO Transport](#stdio-transport)
-    * [Streamable HTTP Transport](#streamable-http-transport)
-    * [SSE Transport](#sse-transport)
-    * [WebSocket Transport](#websocket-transport)
-    * [ChannelTransport (testing)](#channeltransport-testing)
+  * [STDIO Transport](#stdio-transport)
+  * [Streamable HTTP Transport](#streamable-http-transport)
+  * [SSE Transport](#sse-transport)
+  * [WebSocket Transport](#websocket-transport)
+  * [ChannelTransport (testing)](#channeltransport-testing)
 * [Connecting your server](#connecting-your-server)
 * [Examples](#examples)
 * [Documentation](#documentation)
@@ -188,24 +188,19 @@ the [simple-streamable-server](samples/simple-streamable-server) sample.
 <!--- CLEAR -->
 
 ```kotlin
-import io.ktor.serialization.kotlinx.json.json
-import io.ktor.server.application.install
 import io.ktor.server.cio.CIO
 import io.ktor.server.engine.embeddedServer
-import io.ktor.server.plugins.contentnegotiation.ContentNegotiation
 import io.modelcontextprotocol.kotlin.sdk.server.Server
 import io.modelcontextprotocol.kotlin.sdk.server.ServerOptions
 import io.modelcontextprotocol.kotlin.sdk.server.mcpStreamableHttp
 import io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
 import io.modelcontextprotocol.kotlin.sdk.types.Implementation
-import io.modelcontextprotocol.kotlin.sdk.types.McpJson
 import io.modelcontextprotocol.kotlin.sdk.types.ServerCapabilities
 import io.modelcontextprotocol.kotlin.sdk.types.TextContent
 import io.modelcontextprotocol.kotlin.sdk.types.ToolSchema
 import kotlinx.serialization.json.buildJsonObject
 import kotlinx.serialization.json.put
 
-
 fun main(args: Array<String>) {
     val port = args.firstOrNull()?.toIntOrNull() ?: 3000
     val mcpServer = Server(
@@ -231,11 +226,8 @@ fun main(args: Array<String>) {
     ) { request ->
         CallToolResult(content = listOf(TextContent("Hello, world!")))
     }
-
+    
     embeddedServer(CIO, host = "127.0.0.1", port = port) {
-        install(ContentNegotiation) {
-            json(McpJson)
-        }
         mcpStreamableHttp {
             mcpServer
         }
@@ -774,8 +766,10 @@ CLI tooling that spawns a helper process. No networking setup is required.
 
 `StreamableHttpClientTransport` and the Ktor `mcpStreamableHttp()` / `mcpStatelessStreamableHttp()` helpers expose MCP
 over a single HTTP endpoint with optional JSON-only or SSE streaming responses. This is the recommended choice for
-remote deployments and integrates nicely with proxies or service meshes. Both accept a `path` parameter (default:
-`"/mcp"`) to mount the endpoint at any URL:
+remote deployments and integrates nicely with proxies or service meshes.
+
+These helpers automatically install `ContentNegotiation` with `McpJson` — do not install it yourself, or a warning will
+be logged. Both accept a `path` parameter (default: `"/mcp"`) to mount the endpoint at any URL:
 
 <!--- CLEAR -->
 <!--- INCLUDE 
@@ -809,11 +803,30 @@ embeddedServer(CIO, port = 3000) {
 -->
 <!--- KNIT example-server-routes-01.kt -->
 
+**CORS for browser-based clients (e.g. MCP Inspector):** if you connect from a browser-based
+client you need to install the Ktor CORS plugin so that MCP-specific headers are allowed and exposed:
+
+```kotlin
+install(CORS) {
+    anyHost() // restrict to specific origins in production
+    allowMethod(HttpMethod.Options)
+    allowMethod(HttpMethod.Get)
+    allowMethod(HttpMethod.Post)
+    allowMethod(HttpMethod.Delete)
+    allowNonSimpleContentTypes = true
+    allowHeader("Mcp-Session-Id")
+    allowHeader("Mcp-Protocol-Version")
+    exposeHeader("Mcp-Session-Id")
+    exposeHeader("Mcp-Protocol-Version")
+}
+```
+
 ### SSE Transport
 
 Server-Sent Events remain available for backwards compatibility with older MCP clients. Two Ktor helpers are provided:
 
-- **`Application.mcp { }`** — installs the SSE plugin automatically and registers MCP endpoints at `/`.
+- **`Application.mcp { }`** — installs SSE and `ContentNegotiation` with `McpJson` automatically, then registers MCP
+  endpoints at `/`. Do not install `ContentNegotiation` yourself — the SDK handles it.
 - **`Route.mcp { }`** — registers MCP endpoints at the current route path; requires `install(SSE)` in the application
   first. Use this to host MCP alongside other routes or under a path prefix:
 

conformance-test/conformance-baseline.yml

@@ -2,5 +2,4 @@
 # Add entries here as tests are identified as known SDK limitations
 server: []
 
-client:
-  - elicitation-sep1034-client-defaults
+client: []

conformance-test/run-conformance.sh

@@ -9,7 +9,7 @@ set -uo pipefail
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" || exit 1; pwd)"
 PROJECT_ROOT="$(cd "$SCRIPT_DIR/.." || exit 1; pwd)"
 
-CONFORMANCE_VERSION="0.1.15"
+CONFORMANCE_VERSION="0.1.16"
 PORT="${MCP_PORT:-3001}"
 SERVER_URL="http://localhost:${PORT}/mcp"
 RESULTS_DIR="$SCRIPT_DIR/results"

conformance-test/src/main/kotlin/io/modelcontextprotocol/kotlin/sdk/conformance/ConformanceServer.kt

@@ -1,23 +1,16 @@
 package io.modelcontextprotocol.kotlin.sdk.conformance
 
-import io.ktor.serialization.kotlinx.json.json
-import io.ktor.server.application.install
 import io.ktor.server.cio.CIO
 import io.ktor.server.engine.embeddedServer
-import io.ktor.server.plugins.contentnegotiation.ContentNegotiation
 import io.modelcontextprotocol.kotlin.sdk.server.Server
 import io.modelcontextprotocol.kotlin.sdk.server.ServerOptions
 import io.modelcontextprotocol.kotlin.sdk.server.mcpStreamableHttp
 import io.modelcontextprotocol.kotlin.sdk.types.Implementation
-import io.modelcontextprotocol.kotlin.sdk.types.McpJson
 import io.modelcontextprotocol.kotlin.sdk.types.ServerCapabilities
 
 fun main() {
     val port = System.getenv("MCP_PORT")?.toIntOrNull() ?: 3001
     embeddedServer(CIO, port = port) {
-        install(ContentNegotiation) {
-            json(McpJson)
-        }
         mcpStreamableHttp(
             enableDnsRebindingProtection = true,
             allowedHosts = listOf("localhost", "127.0.0.1", "localhost:$port", "127.0.0.1:$port"),