feat: add resource link

Author: bzsurbhi

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

@@ -1473,8 +1473,9 @@ public record CompleteCompletion(
 	@JsonSubTypes({ @JsonSubTypes.Type(value = TextContent.class, name = "text"),
 			@JsonSubTypes.Type(value = ImageContent.class, name = "image"),
 			@JsonSubTypes.Type(value = AudioContent.class, name = "audio"),
-			@JsonSubTypes.Type(value = EmbeddedResource.class, name = "resource") })
-	public sealed interface Content permits TextContent, ImageContent, AudioContent, EmbeddedResource {
+			@JsonSubTypes.Type(value = EmbeddedResource.class, name = "resource"),
+			@JsonSubTypes.Type(value = ResourceLink.class, name = "resource_link") })
+	public sealed interface Content permits TextContent, ImageContent, AudioContent, EmbeddedResource, ResourceLink {
 
 		default String type() {
 			if (this instanceof TextContent) {
@@ -1489,6 +1490,9 @@ else if (this instanceof AudioContent) {
 			else if (this instanceof EmbeddedResource) {
 				return "resource";
 			}
+			else if (this instanceof ResourceLink) {
+				return "resource_link";
+			}
 			throw new IllegalArgumentException("Unknown content type: " + this);
 		}
 
@@ -1601,6 +1605,18 @@ public Double priority() {
 		}
 	}
 
+	@JsonInclude(JsonInclude.Include.NON_ABSENT)
+	@JsonIgnoreProperties(ignoreUnknown = true)
+	public record ResourceLink( // @formatter:off
+		@JsonProperty("name") String name,
+		@JsonProperty("title") String title,
+		@JsonProperty("uri") String uri,
+		@JsonProperty("description") String description,
+		@JsonProperty("mimeType") String mimeType,
+		@JsonProperty("annotations") Annotations annotations,
+		@JsonProperty("size") Integer size) implements Annotated, Content { // @formatter:on
+	}
+
 	// ---------------------------
 	// Roots
 	// ---------------------------

mcp/src/test/java/io/modelcontextprotocol/spec/McpSchemaTests.java

@@ -60,7 +60,7 @@ void testContentDeserializationWrongType() throws Exception {
 				{"type":"WRONG","text":"XXX"}""", McpSchema.TextContent.class))
 			.isInstanceOf(InvalidTypeIdException.class)
 			.hasMessageContaining(
-					"Could not resolve type id 'WRONG' as a subtype of `io.modelcontextprotocol.spec.McpSchema$TextContent`: known type ids = [audio, image, resource, text]");
+					"Could not resolve type id 'WRONG' as a subtype of `io.modelcontextprotocol.spec.McpSchema$TextContent`: known type ids = [audio, image, resource, resource_link, text]");
 	}
 
 	@Test
@@ -168,6 +168,36 @@ void testEmbeddedResourceWithBlobContentsDeserialization() throws Exception {
 			.isEqualTo("base64encodedblob");
 	}
 
+	@Test
+	void testResourceLink() throws Exception {
+		McpSchema.ResourceLink resourceLink = new McpSchema.ResourceLink("main.rs",
+				"Rust Software Application Main File", "file:///project/src/main.rs", "Primary application entry point",
+				"text/x-rust", null, null);
+		String value = mapper.writeValueAsString(resourceLink);
+
+		assertThatJson(value).when(Option.IGNORING_ARRAY_ORDER)
+			.when(Option.IGNORING_EXTRA_ARRAY_ITEMS)
+			.isObject()
+			.isEqualTo(
+					json("""
+							{"type":"resource_link","name":"main.rs","title":"Rust Software Application Main File","uri":"file:///project/src/main.rs","description":"Primary application entry point","mimeType":"text/x-rust"}"""));
+	}
+
+	@Test
+	void testResourceLinkDeserialization() throws Exception {
+		McpSchema.ResourceLink resourceLink = mapper.readValue(
+				"""
+						{"type":"resource_link","name":"main.rs","title":"Rust Software Application Main File","uri":"file:///project/src/main.rs","description":"Primary application entry point","mimeType":"text/x-rust"}""",
+				McpSchema.ResourceLink.class);
+		assertThat(resourceLink).isNotNull();
+		assertThat(resourceLink.type()).isEqualTo("resource_link");
+		assertThat(resourceLink.name()).isEqualTo("main.rs");
+		assertThat(resourceLink.title()).isEqualTo("Rust Software Application Main File");
+		assertThat(resourceLink.uri()).isEqualTo("file:///project/src/main.rs");
+		assertThat(resourceLink.description()).isEqualTo("Primary application entry point");
+		assertThat(resourceLink.mimeType()).isEqualTo("text/x-rust");
+	}
+
 	// JSON-RPC Message Types Tests
 
 	@Test