Support non-String URI variable parameters for @McpResource methods

mcp/mcp-annotations/src/main/java/org/springframework/ai/mcp/annotation/method/resource/AbstractMcpResourceMethodCallback.java

@@ -368,23 +368,6 @@ else if (McpAsyncRequestContext.class.isAssignableFrom(paramType)) {
 							+ " in " + method.getDeclaringClass().getName() + ". URI variables: " + this.uriVariables);
 		}
 
-		// Check that all non-special parameters are String type (for URI variables)
-		for (Parameter param : parameters) {
-			// Skip @McpProgressToken annotated parameters
-			if (param.isAnnotationPresent(McpProgressToken.class)) {
-				continue;
-			}
-
-			Class<?> paramType = param.getType();
-			if (!McpSyncRequestContext.class.isAssignableFrom(paramType)
-					&& !McpAsyncRequestContext.class.isAssignableFrom(paramType) && !isExchangeOrContextType(paramType)
-					&& !ReadResourceRequest.class.isAssignableFrom(paramType)
-					&& !McpMeta.class.isAssignableFrom(paramType) && !String.class.isAssignableFrom(paramType)) {
-				throw new IllegalArgumentException("URI variable parameters must be of type String: " + method.getName()
-						+ " in " + method.getDeclaringClass().getName() + ", parameter of type " + paramType.getName()
-						+ " is not valid");
-			}
-		}
 	}
 
 	protected abstract Object assignExchangeType(Class<?> paramType, Object exchange);
@@ -492,7 +475,8 @@ protected void buildArgsWithUriVariables(Parameter[] parameters, Object[] args,
 			// Assign the next URI variable
 			if (variableIndex < this.uriVariables.size()) {
 				String variableName = this.uriVariables.get(variableIndex);
-				args[i] = uriVariableValues.get(variableName);
+				args[i] = McpUriVariableValueConverter.convert(uriVariableValues.get(variableName),
+						parameters[i].getType());
 				assignedVariables.add(variableName);
 				variableIndex++;
 			}

mcp/mcp-annotations/src/main/java/org/springframework/ai/mcp/annotation/method/resource/McpUriVariableValueConverter.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2023-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.ai.mcp.annotation.method.resource;
+
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.core.convert.ConversionFailedException;
+import org.springframework.core.convert.ConversionService;
+import org.springframework.core.convert.TypeDescriptor;
+import org.springframework.core.convert.support.DefaultConversionService;
+import org.springframework.util.Assert;
+
+/**
+ * Converts URI template variable values to method parameter types.
+ *
+ * @author yubishen
+ */
+final class McpUriVariableValueConverter {
+
+	private static final ConversionService CONVERSION_SERVICE = new DefaultConversionService();
+
+	private McpUriVariableValueConverter() {
+	}
+
+	static Object convert(@Nullable String value, Class<?> targetType) {
+		Assert.notNull(targetType, "targetType cannot be null");
+
+		if (String.class.equals(targetType)) {
+			return value;
+		}
+
+		try {
+			Object converted = CONVERSION_SERVICE.convert(value, targetType);
+			if (converted == null && value != null) {
+				throw new ConversionFailedException(TypeDescriptor.valueOf(String.class),
+						TypeDescriptor.valueOf(targetType), value,
+						new IllegalArgumentException("Conversion returned null"));
+			}
+			return converted;
+		}
+		catch (ConversionFailedException ex) {
+			throw new IllegalArgumentException(
+					"Failed to convert URI variable value '%s' to %s".formatted(value, targetType.getName()), ex);
+		}
+	}
+
+}

mcp/mcp-annotations/src/test/java/org/springframework/ai/mcp/annotation/method/resource/SyncMcpResourceMethodCallbackTests.java

@@ -220,6 +220,50 @@ public void testCallbackWithUriVariables() throws Exception {
 		assertThat(textContent.text()).isEqualTo("User: 123, Post: 456");
 	}
 
+	@Test
+	public void testCallbackWithIntegerUriVariable() throws Exception {
+		TestResourceProvider provider = new TestResourceProvider();
+		Method method = TestResourceProvider.class.getMethod("getUserByIntId", int.class);
+		McpResource resourceAnnotation = method.getAnnotation(McpResource.class);
+
+		BiFunction<McpSyncServerExchange, ReadResourceRequest, ReadResourceResult> callback = SyncMcpResourceMethodCallback
+			.builder()
+			.method(method)
+			.bean(provider)
+			.resource(ResourceAdapter.asResource(resourceAnnotation))
+			.build();
+
+		McpSyncServerExchange exchange = mock(McpSyncServerExchange.class);
+		ReadResourceRequest request = ReadResourceRequest.builder("example.com/users/42").build();
+
+		ReadResourceResult result = callback.apply(exchange, request);
+
+		assertThat(result).isNotNull();
+		assertThat(result.contents()).hasSize(1);
+		assertThat(result.contents().get(0)).isInstanceOf(TextResourceContents.class);
+		TextResourceContents textContent = (TextResourceContents) result.contents().get(0);
+		assertThat(textContent.text()).isEqualTo("User id: 42");
+	}
+
+	@Test
+	public void testCallbackWithInvalidIntegerUriVariable() throws Exception {
+		TestResourceProvider provider = new TestResourceProvider();
+		Method method = TestResourceProvider.class.getMethod("getUserByIntId", int.class);
+		McpResource resourceAnnotation = method.getAnnotation(McpResource.class);
+
+		BiFunction<McpSyncServerExchange, ReadResourceRequest, ReadResourceResult> callback = SyncMcpResourceMethodCallback
+			.builder()
+			.method(method)
+			.bean(provider)
+			.resource(ResourceAdapter.asResource(resourceAnnotation))
+			.build();
+
+		McpSyncServerExchange exchange = mock(McpSyncServerExchange.class);
+		ReadResourceRequest request = ReadResourceRequest.builder("example.com/users/not-a-number").build();
+
+		assertThatThrownBy(() -> callback.apply(exchange, request)).isInstanceOf(McpError.class);
+	}
+
 	@Test
 	public void testCallbackWithExchangeAndUriVariable() throws Exception {
 		TestResourceProvider provider = new TestResourceProvider();
@@ -1272,6 +1316,15 @@ public ReadResourceResult getResourceWithUriVariables(String userId, String post
 				.build())).build();
 		}
 
+		@McpResource(uri = "example.com/users/{id}")
+		public ReadResourceResult getUserByIntId(int id) {
+			return ReadResourceResult
+				.builder(List.of(TextResourceContents.builder("example.com/users/" + id, "User id: " + id)
+					.mimeType("text/plain")
+					.build()))
+				.build();
+		}
+
 		@McpResource(uri = "users/{userId}/profile")
 		public ReadResourceResult getResourceWithExchangeAndUriVariable(McpSyncServerExchange exchange, String userId) {
 			return ReadResourceResult.builder(