Polish gh-764

Signed-off-by: Daniel Garnier-Moiroux <git@garnier.wf>

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

@@ -1466,6 +1466,7 @@ public final class McpSchema {
 			}
 
 			public Tool build() {
+				Assert.hasText(name, "name must not be empty");
 				return new Tool(name, title, description, inputSchema, outputSchema, annotations, meta);
 			}