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

Author: amaan75

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

@@ -377,12 +377,13 @@ public Mono<Void> addTools(List<McpServerFeatures.AsyncToolSpecification> toolSp
 		if (toolSpecifications == null) {
 			return Mono.error(new IllegalArgumentException("Tool specifications must not be null"));
 		}
-		if (toolSpecifications.isEmpty()) {
-			return Mono.empty();
-		}
+
 		if (this.serverCapabilities.tools() == null) {
 			return Mono.error(new IllegalStateException("Server must be configured with tool capabilities"));
 		}
+		if (toolSpecifications.isEmpty()) {
+			return Mono.empty();
+		}
 
 		Map<String, McpServerFeatures.AsyncToolSpecification> wrappedToolSpecificationsByName;
 		try {

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

@@ -366,13 +366,14 @@ public Mono<Void> addTools(List<McpStatelessServerFeatures.AsyncToolSpecificatio
 		if (toolSpecifications == null) {
 			return Mono.error(new IllegalArgumentException("Tool specifications must not be null"));
 		}
-		if (toolSpecifications.isEmpty()) {
-			return Mono.empty();
-		}
 		if (this.serverCapabilities.tools() == null) {
 			return Mono.error(new IllegalStateException("Server must be configured with tool capabilities"));
 		}
 
+		if (toolSpecifications.isEmpty()) {
+			return Mono.empty();
+		}
+
 		Map<String, McpStatelessServerFeatures.AsyncToolSpecification> wrappedToolSpecificationsByName;
 		try {
 			wrappedToolSpecificationsByName = sanitizeToolSpecifications(toolSpecifications);