diff --git a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java
index dd7c6539..5ed82228 100644
--- a/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java
+++ b/mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java
@@ -36,6 +36,9 @@
 import reactor.util.function.Tuple2;
 import reactor.util.function.Tuples;
 
+import static io.modelcontextprotocol.spec.McpSchema.Headers.LAST_EVENT_ID;
+import static io.modelcontextprotocol.spec.McpSchema.Headers.MCP_SESSION_ID;
+
 /**
  * An implementation of the Streamable HTTP protocol as defined by the
  * <code>2025-03-26</code> version of the MCP specification.
@@ -128,7 +131,7 @@ public Mono<Void> connect(Function<Mono<McpSchema.JSONRPCMessage>, Mono<McpSchem
 	private DefaultMcpTransportSession createTransportSession() {
 		Function<String, Publisher<Void>> onClose = sessionId -> sessionId == null ? Mono.empty()
 				: webClient.delete().uri(this.endpoint).headers(httpHeaders -> {
-					httpHeaders.add("mcp-session-id", sessionId);
+					httpHeaders.add(MCP_SESSION_ID, sessionId);
 				})
 					.retrieve()
 					.toBodilessEntity()
@@ -187,9 +190,9 @@ private Mono<Disposable> reconnect(McpTransportStream<Disposable> stream) {
 				.uri(this.endpoint)
 				.accept(MediaType.TEXT_EVENT_STREAM)
 				.headers(httpHeaders -> {
-					transportSession.sessionId().ifPresent(id -> httpHeaders.add("mcp-session-id", id));
+					transportSession.sessionId().ifPresent(id -> httpHeaders.add(MCP_SESSION_ID, id));
 					if (stream != null) {
-						stream.lastId().ifPresent(id -> httpHeaders.add("last-event-id", id));
+						stream.lastId().ifPresent(id -> httpHeaders.add(LAST_EVENT_ID, id));
 					}
 				})
 				.exchangeToFlux(response -> {
@@ -247,12 +250,11 @@ public Mono<Void> sendMessage(McpSchema.JSONRPCMessage message) {
 				.uri(this.endpoint)
 				.accept(MediaType.TEXT_EVENT_STREAM, MediaType.APPLICATION_JSON)
 				.headers(httpHeaders -> {
-					transportSession.sessionId().ifPresent(id -> httpHeaders.add("mcp-session-id", id));
+					transportSession.sessionId().ifPresent(id -> httpHeaders.add(MCP_SESSION_ID, id));
 				})
 				.bodyValue(message)
 				.exchangeToFlux(response -> {
-					if (transportSession
-						.markInitialized(response.headers().asHttpHeaders().getFirst("mcp-session-id"))) {
+					if (transportSession.markInitialized(response.headers().asHttpHeaders().getFirst(MCP_SESSION_ID))) {
 						// Once we have a session, we try to open an async stream for
 						// the server to send notifications and requests out-of-band.
 						reconnect(null).contextWrite(sink.contextView()).subscribe();
diff --git a/mcp/src/main/java/io/modelcontextprotocol/spec/McpSchema.java b/mcp/src/main/java/io/modelcontextprotocol/spec/McpSchema.java
index 59713094..cda76531 100644
--- a/mcp/src/main/java/io/modelcontextprotocol/spec/McpSchema.java
+++ b/mcp/src/main/java/io/modelcontextprotocol/spec/McpSchema.java
@@ -141,6 +141,28 @@ public static final class ErrorCodes {
 
 	}
 
+	// ---------------------------
+	// JSON-RPC Protocol Headers
+	// ---------------------------
+	/**
+	 * Standard header name used in MCP JSON-RPC request and responses.
+	 */
+	public static final class Headers {
+
+		/**
+		 * The Model Context Protocol (MCP) session ID header name.
+		 */
+		public static final String MCP_SESSION_ID = "Mcp-Session-Id";
+
+		/**
+		 * The Last-Event-ID HTTP request header reports an EventSource object's last
+		 * event ID string to the server when the user agent is to reestablish the
+		 * connection.
+		 */
+		public static final String LAST_EVENT_ID = "Last-Event-ID";
+
+	}
+
 	public sealed interface Request permits InitializeRequest, CallToolRequest, CreateMessageRequest, ElicitRequest,
 			CompleteRequest, GetPromptRequest {