Relocate tool capability validation to ensure early exit in async server methods

Author: amaan75

mcp-core/src/main/java/io/modelcontextprotocol/server/McpAsyncServer.java

@@ -380,6 +380,9 @@ public Mono<Void> addTools(List<McpServerFeatures.AsyncToolSpecification> toolSp
 		if (toolSpecifications.isEmpty()) {
 			return Mono.empty();
 		}
+		if (this.serverCapabilities.tools() == null) {
+			return Mono.error(new IllegalStateException("Server must be configured with tool capabilities"));
+		}
 
 		Map<String, McpServerFeatures.AsyncToolSpecification> wrappedToolSpecificationsByName;
 		try {
@@ -388,9 +391,6 @@ public Mono<Void> addTools(List<McpServerFeatures.AsyncToolSpecification> toolSp
 		catch (IllegalArgumentException e) {
 			return Mono.error(e);
 		}
-		if (this.serverCapabilities.tools() == null) {
-			return Mono.error(new IllegalStateException("Server must be configured with tool capabilities"));
-		}
 
 		return Mono.defer(() -> {
 			this.tools.removeIf(

mcp-core/src/main/java/io/modelcontextprotocol/server/McpStatelessAsyncServer.java

@@ -369,6 +369,9 @@ public Mono<Void> addTools(List<McpStatelessServerFeatures.AsyncToolSpecificatio
 		if (toolSpecifications.isEmpty()) {
 			return Mono.empty();
 		}
+		if (this.serverCapabilities.tools() == null) {
+			return Mono.error(new IllegalStateException("Server must be configured with tool capabilities"));
+		}
 
 		Map<String, McpStatelessServerFeatures.AsyncToolSpecification> wrappedToolSpecificationsByName;
 		try {
@@ -377,9 +380,6 @@ public Mono<Void> addTools(List<McpStatelessServerFeatures.AsyncToolSpecificatio
 		catch (IllegalArgumentException e) {
 			return Mono.error(e);
 		}
-		if (this.serverCapabilities.tools() == null) {
-			return Mono.error(new IllegalStateException("Server must be configured with tool capabilities"));
-		}
 
 		return Mono.defer(() -> {
 			this.tools.removeIf(