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c61a7ca00cBumps `mcp-kotlin` from 0.14.0 to 0.15.0. Updates `io.modelcontextprotocol:kotlin-sdk-client` from 0.14.0 to 0.15.0 <details> <summary>Release notes</summary> <p><em>Sourced from <a href="https://github.com/modelcontextprotocol/kotlin-sdk/releases">io.modelcontextprotocol:kotlin-sdk-client's releases</a>.</em></p> <blockquote> <h2>0.15.0</h2> <h2>Description</h2> <p>This release makes inbound message handling concurrent after the initialization handshake, adds SSE heartbeats and elicitation schema validation, and fixes several Streamable HTTP response and session-lifecycle bugs.</p> <h3>Breaking Changes</h3> <p><strong>Concurrent inbound dispatch</strong> by <a href="https://github.com/devcrocod"><code>@devcrocod</code></a> in <a href="https://redirect.github.com/modelcontextprotocol/kotlin-sdk/pull/884">#884</a></p> <p>Inbound messages were processed serially on the transport read loop, so one slow or peer-awaiting handler (sampling, elicitation, roots) blocked every later message on the connection, including the responses and <code>notifications/cancelled</code> those handlers depend on. After the handshake, handlers may now run concurrently; processing stays serial during initialization.</p> <ul> <li><code>ProtocolOptions</code> / <code>ClientOptions</code> / <code>ServerOptions</code> gain a <code>handlerCoroutineContext</code> parameter (defaults to <code>Dispatchers.Default</code>). Concurrency is bounded internally; there is no opt-out flag by design.</li> <li><code>RequestHandlerExtra</code> is now a <code>CoroutineContext.Element</code> and is no longer user-constructible. It exposes <code>requestId</code>, <code>method</code>, <code>sendRequest</code>, and <code>sendNotification</code>, and can be read inside a handler via the new <code>currentRequestHandlerExtra()</code>.</li> </ul> <pre lang="diff"><code>- val extra = RequestHandlerExtra() + val extra = currentRequestHandlerExtra() </code></pre> <p><strong>Duplicate feature names are rejected at registration</strong> by <a href="https://github.com/devcrocod"><code>@devcrocod</code></a> in <a href="https://redirect.github.com/modelcontextprotocol/kotlin-sdk/pull/883">#883</a></p> <p><code>addTool</code>/<code>addPrompt</code>/<code>addResource</code>/<code>addResourceTemplate</code> silently replaced an existing entry and emitted a spurious <code>list_changed</code> notification. They now throw <code>IllegalArgumentException</code> and leave the existing registration intact. The batch variants (<code>addTools</code>/<code>addPrompts</code>/<code>addResources</code>) are all-or-nothing. To replace a feature, remove it first.</p> <pre lang="diff"><code>- server.addTool(name = "search", ...) // silently overwrote + server.removeTool("search") + server.addTool(name = "search", ...) </code></pre> <p><strong><code>eventStore</code> removed from <code>mcpStatelessStreamableHttp</code></strong> by <a href="https://github.com/devcrocod"><code>@devcrocod</code></a> in <a href="https://redirect.github.com/modelcontextprotocol/kotlin-sdk/pull/909">#909</a></p> <p>The parameter was never read or written: a stateless endpoint answers <code>GET</code> with <code>405</code>, so no stream exists to store or replay events on. The old overload is retained at <code>DeprecationLevel.ERROR</code> with a <code>ReplaceWith</code> migration hint. Use <code>mcpStreamableHttp</code> when you need resumability.</p> <pre lang="diff"><code> application.mcpStatelessStreamableHttp( path = "/mcp", - eventStore = myEventStore, ) { server } </code></pre> <h3>Features</h3> <ul> <li>Optional SSE heartbeats for Streamable HTTP servers via <code>mcpStreamableHttp(sseHeartbeatConfig = { ... })</code>, keeping long-lived streams alive against clients that disconnect on idle. Heartbeats stay off by default, by <a href="https://github.com/UnscientificJsZhai"><code>@UnscientificJsZhai</code></a> in <a href="https://redirect.github.com/modelcontextprotocol/kotlin-sdk/pull/761">#761</a></li> <li>Accepted form-mode elicitation content is now validated against <code>requestedSchema</code>; a mismatch fails <code>createElicitation</code> with <code>McpException</code> (<code>INVALID_PARAMS</code>) instead of reaching server code unchecked, by <a href="https://github.com/rea9r"><code>@rea9r</code></a> in <a href="https://redirect.github.com/modelcontextprotocol/kotlin-sdk/pull/896">#896</a></li> <li>The Streamable HTTP client now sends the standard <code>Mcp-Method</code> and <code>Mcp-Name</code> POST headers, by <a href="https://github.com/AndreKalberer"><code>@AndreKalberer</code></a> in <a href="https://redirect.github.com/modelcontextprotocol/kotlin-sdk/pull/894">#894</a></li> </ul> <h3>Fixed</h3> <ul> <li>Stateless Streamable HTTP now closes its per-request session, fixing unbounded growth of the session registry and notification subscriptions, by <a href="https://github.com/KlyneChrysler"><code>@KlyneChrysler</code></a> in <a href="https://redirect.github.com/modelcontextprotocol/kotlin-sdk/pull/872">#872</a></li> <li>Streamable HTTP responses keep their status and body when the client accepts only <code>text/event-stream</code>, by <a href="https://github.com/devcrocod"><code>@devcrocod</code></a> in <a href="https://redirect.github.com/modelcontextprotocol/kotlin-sdk/pull/911">#911</a></li> </ul> <!-- raw HTML omitted --> </blockquote> <p>... 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| kotlin-mcp-client | ||
| kotlin-mcp-server | ||
| kotlinlang-mcp-server | ||
| notebooks | ||
| simple-streamable-server | ||
| weather-stdio-server | ||
| README.md | ||
Kotlin MCP SDK Samples
Runnable projects demonstrating MCP server and client implementations with the Kotlin MCP SDK. For background on the protocol itself, see the MCP documentation.
Overview
| Sample | Type | Transport | MCP Features |
|---|---|---|---|
| simple-streamable-server | Server | Streamable HTTP | Tools, Resources, Prompts, Logging |
| kotlinlang-mcp-server | Server | Streamable HTTP | Tools |
| kotlin-mcp-server | Server | STDIO, SSE | Tools, Resources, Prompts |
| weather-stdio-server | Server | STDIO | Tools |
| kotlin-mcp-client | Client | STDIO | Tool discovery & invocation |
| notebooks | Client (Notebook) | Streamable HTTP | Tool discovery & invocation |
Getting Started
- Building a server? Start with simple-streamable-server — it uses the recommended Streamable HTTP transport and covers tools, resources, prompts, and logging.
- Building a client? Open the notebooks sample for a step-by-step walkthrough, or see kotlin-mcp-client for a full CLI client with Anthropic API integration.
Samples
Simple Streamable HTTP Server
A minimal Streamable HTTP server with optional Bearer token authentication. Demonstrates tools
(greet, multi-greet), a prompt template, a resource, and server-to-client logging notifications.
Read more →
Kotlinlang MCP Server
A Streamable HTTP server that exposes the official Kotlin documentation (kotlinlang.org) to LLM clients — full-text search via Algolia and page retrieval in markdown. Demonstrates wrapping a real external API in an MCP server with in-memory caching. Read more →
Kotlin MCP Server
A multi-transport server supporting STDIO, SSE (plain), and SSE (Ktor plugin). Useful for exploring different transport modes side by side. Read more →
Weather STDIO Server
A focused STDIO server that exposes weather forecast and alert tools backed by the weather.gov API. Includes Claude Desktop integration instructions. Read more →
Kotlin MCP Client
An interactive CLI client that connects to any MCP server over STDIO and routes queries through Anthropic's Claude API, bridging MCP tools with LLM conversations. Read more →
MCP Client Notebook
A Kotlin notebook that connects to a remote MCP server via Streamable HTTP and demonstrates ping, tool listing, and tool invocation — all in an interactive cell-by-cell format. Read more →