feat(mcp-core): support Mcp-Name header for Streamable HTTP (SEP-2243)

mcp-core/src/main/java/io/modelcontextprotocol/client/transport/HttpClientStreamableHttpTransport.java

@@ -483,14 +483,34 @@ public Mono<Void> sendMessage(McpSchema.JSONRPCMessage sentMessage) {
 							transportSession.sessionId().get());
 				}
 
+				// Extract method and params for Mcp-Name header
+				String method = null;
+				Object params = null;
+				if (sentMessage instanceof McpSchema.JSONRPCRequest request) {
+					method = request.method();
+					params = request.params();
+				}
+				else if (sentMessage instanceof McpSchema.JSONRPCNotification notification) {
+					method = notification.method();
+					params = notification.params();
+				}
+
 				var builder = requestBuilder.uri(uri)
 					.header(HttpHeaders.ACCEPT, APPLICATION_JSON + ", " + TEXT_EVENT_STREAM)
 					.header(HttpHeaders.CONTENT_TYPE, APPLICATION_JSON_UTF8)
 					.header(HttpHeaders.CACHE_CONTROL, "no-cache")
-					.header(HttpHeaders.PROTOCOL_VERSION,
-							ctx.getOrDefault(McpAsyncClient.NEGOTIATED_PROTOCOL_VERSION,
-									this.latestSupportedProtocolVersion))
-					.POST(HttpRequest.BodyPublishers.ofString(jsonBody));
+					.header(HttpHeaders.PROTOCOL_VERSION, ctx.getOrDefault(McpAsyncClient.NEGOTIATED_PROTOCOL_VERSION,
+							this.latestSupportedProtocolVersion));
+
+				// Add Mcp-Name header if applicable
+				if (method != null) {
+					String name = extractNameFromParams(method, params);
+					if (name != null) {
+						builder = builder.header(HttpHeaders.MCP_NAME, name);
+					}
+				}
+
+				builder = builder.POST(HttpRequest.BodyPublishers.ofString(jsonBody));
 				var transportContext = ctx.getOrDefault(McpTransportContext.KEY, McpTransportContext.EMPTY);
 				return Mono
 					.from(this.httpRequestCustomizer.customize(builder, "POST", uri, jsonBody, transportContext));
@@ -675,6 +695,48 @@ public <T> T unmarshalFrom(Object data, TypeRef<T> typeRef) {
 		return this.jsonMapper.convertValue(data, typeRef);
 	}
 
+	/**
+	 * Extracts the name/URI from the request params based on the method type.
+	 * @param method the MCP method name
+	 * @param params the request parameters
+	 * @return the name/URI if applicable for the method, or null otherwise
+	 */
+	private String extractNameFromParams(String method, Object params) {
+		if (params == null) {
+			return null;
+		}
+
+		try {
+			switch (method) {
+				case McpSchema.METHOD_TOOLS_CALL -> {
+					McpSchema.CallToolRequest request = this.jsonMapper.convertValue(params,
+							new TypeRef<McpSchema.CallToolRequest>() {
+							});
+					return request.name();
+				}
+				case McpSchema.METHOD_RESOURCES_READ -> {
+					McpSchema.ReadResourceRequest request = this.jsonMapper.convertValue(params,
+							new TypeRef<McpSchema.ReadResourceRequest>() {
+							});
+					return request.uri();
+				}
+				case McpSchema.METHOD_PROMPT_GET -> {
+					McpSchema.GetPromptRequest request = this.jsonMapper.convertValue(params,
+							new TypeRef<McpSchema.GetPromptRequest>() {
+							});
+					return request.name();
+				}
+				default -> {
+					return null;
+				}
+			}
+		}
+		catch (Exception e) {
+			logger.debug("Failed to extract name from params for method {}: {}", method, e.getMessage());
+			return null;
+		}
+	}
+
 	/**
 	 * Builder for {@link HttpClientStreamableHttpTransport}.
 	 */

mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStreamableServerTransportProvider.java

@@ -390,6 +390,42 @@ public void onStartAsync(jakarta.servlet.AsyncEvent event) throws IOException {
 	 * @throws ServletException If a servlet-specific error occurs
 	 * @throws IOException If an I/O error occurs
 	 */
+	private String extractNameFromParams(String method, Object params) {
+		if (params == null) {
+			return null;
+		}
+
+		try {
+			switch (method) {
+				case McpSchema.METHOD_TOOLS_CALL -> {
+					McpSchema.CallToolRequest request = jsonMapper.convertValue(params,
+							new TypeRef<McpSchema.CallToolRequest>() {
+							});
+					return request.name();
+				}
+				case McpSchema.METHOD_RESOURCES_READ -> {
+					McpSchema.ReadResourceRequest request = jsonMapper.convertValue(params,
+							new TypeRef<McpSchema.ReadResourceRequest>() {
+							});
+					return request.uri();
+				}
+				case McpSchema.METHOD_PROMPT_GET -> {
+					McpSchema.GetPromptRequest request = jsonMapper.convertValue(params,
+							new TypeRef<McpSchema.GetPromptRequest>() {
+							});
+					return request.name();
+				}
+				default -> {
+					return null;
+				}
+			}
+		}
+		catch (Exception e) {
+			logger.debug("Failed to extract name from params for method {}: {}", method, e.getMessage());
+			return null;
+		}
+	}
+
 	@Override
 	protected void doPost(HttpServletRequest request, HttpServletResponse response)
 			throws ServletException, IOException {
@@ -436,6 +472,32 @@ protected void doPost(HttpServletRequest request, HttpServletResponse response)
 
 			McpSchema.JSONRPCMessage message = McpSchema.deserializeJsonRpcMessage(jsonMapper, body.toString());
 
+			if (message instanceof McpSchema.JSONRPCRequest jsonrpcRequest) {
+				String method = jsonrpcRequest.method();
+				if (McpSchema.METHOD_TOOLS_CALL.equals(method) || McpSchema.METHOD_RESOURCES_READ.equals(method)
+						|| McpSchema.METHOD_PROMPT_GET.equals(method)) {
+					String expectedName = extractNameFromParams(method, jsonrpcRequest.params());
+					String headerName = request.getHeader(HttpHeaders.MCP_NAME);
+
+					if (headerName == null || headerName.isBlank()) {
+						this.responseError(response, HttpServletResponse.SC_BAD_REQUEST,
+								McpError.builder(McpSchema.ErrorCodes.INVALID_REQUEST)
+									.message("Mcp-Name header required for method " + method)
+									.build());
+						return;
+					}
+
+					if (expectedName == null || !headerName.equals(expectedName)) {
+						this.responseError(response, HttpServletResponse.SC_BAD_REQUEST,
+								McpError.builder(McpSchema.ErrorCodes.INVALID_REQUEST)
+									.message("Mcp-Name header mismatch: expected '" + expectedName + "' but was '"
+											+ headerName + "'")
+									.build());
+						return;
+					}
+				}
+			}
+
 			// Handle initialization request
 			if (message instanceof McpSchema.JSONRPCRequest jsonrpcRequest
 					&& jsonrpcRequest.method().equals(McpSchema.METHOD_INITIALIZE)) {

mcp-core/src/main/java/io/modelcontextprotocol/spec/HttpHeaders.java

@@ -26,6 +26,11 @@ public interface HttpHeaders {
 	 */
 	String PROTOCOL_VERSION = "MCP-Protocol-Version";
 
+	/**
+	 * The name or URI of the resource/tool/prompt being accessed.
+	 */
+	String MCP_NAME = "Mcp-Name";
+
 	/**
 	 * The HTTP Content-Length header.
 	 * @see <a href=