(flink-agents) branch main updated: [hotfix][mcp] Skip listPrompts for MCP servers without prompt support (#539)

[xtsong]

This is an automated email from the ASF dual-hosted git repository.

xtsong pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/flink-agents.git


The following commit(s) were added to refs/heads/main by this push:
     new eed00ce6 [hotfix][mcp] Skip listPrompts for MCP servers without prompt 
support (#539)
eed00ce6 is described below

commit eed00ce6d4f6cd245ad5a98f32818a2068daec77
Author: Avichay Marciano <martzi...@gmail.com>
AuthorDate: Wed Mar 4 09:11:50 2026 +0200

    [hotfix][mcp] Skip listPrompts for MCP servers without prompt support (#539)
---
 .../flink/agents/integrations/mcp/MCPServer.java      | 19 +++++++++++++++++++
 .../flink/agents/integrations/mcp/MCPServerTest.java  | 11 +++++++++++
 2 files changed, 30 insertions(+)

diff --git 
a/integrations/mcp/src/main/java/org/apache/flink/agents/integrations/mcp/MCPServer.java
 
b/integrations/mcp/src/main/java/org/apache/flink/agents/integrations/mcp/MCPServer.java
index faa03411..ea3eb01e 100644
--- 
a/integrations/mcp/src/main/java/org/apache/flink/agents/integrations/mcp/MCPServer.java
+++ 
b/integrations/mcp/src/main/java/org/apache/flink/agents/integrations/mcp/MCPServer.java
@@ -42,6 +42,7 @@ import java.net.URI;
 import java.net.http.HttpRequest;
 import java.time.Duration;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -360,6 +361,21 @@ public class MCPServer extends Resource {
         }
     }
 
+    /**
+     * Check if the MCP server supports prompts based on its declared 
capabilities.
+     *
+     * @return true if the server declared prompt capabilities during 
initialization
+     */
+    public boolean supportsPrompts() {
+        try {
+            McpSyncClient mcpClient = getClient();
+            McpSchema.ServerCapabilities caps = 
mcpClient.getServerCapabilities();
+            return caps != null && caps.prompts() != null;
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
     /**
      * List available tools from the MCP server.
      *
@@ -456,6 +472,9 @@ public class MCPServer extends Resource {
      * @return List of MCPPrompt instances
      */
     public List<MCPPrompt> listPrompts() {
+        if (!supportsPrompts()) {
+            return Collections.emptyList();
+        }
         return getRetryExecutor()
                 .execute(
                         () -> {
diff --git 
a/integrations/mcp/src/test/java/org/apache/flink/agents/integrations/mcp/MCPServerTest.java
 
b/integrations/mcp/src/test/java/org/apache/flink/agents/integrations/mcp/MCPServerTest.java
index 85300386..6ae3a23e 100644
--- 
a/integrations/mcp/src/test/java/org/apache/flink/agents/integrations/mcp/MCPServerTest.java
+++ 
b/integrations/mcp/src/test/java/org/apache/flink/agents/integrations/mcp/MCPServerTest.java
@@ -30,6 +30,7 @@ import org.junit.jupiter.api.condition.JRE;
 
 import java.time.Duration;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import static 
com.fasterxml.jackson.databind.DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES;
@@ -270,4 +271,14 @@ class MCPServerTest {
         assertThat(server.getInitialBackoffMs()).isEqualTo(200);
         assertThat(server.getMaxBackoffMs()).isEqualTo(5000);
     }
+
+    @Test
+    @DisabledOnJre(JRE.JAVA_11)
+    @DisplayName("listPrompts returns empty list when server does not support 
prompts")
+    void testListPromptsReturnsEmptyWhenNotSupported() {
+        MCPServer server = MCPServer.builder(DEFAULT_ENDPOINT).build();
+
+        List<MCPPrompt> prompts = server.listPrompts();
+        assertThat(prompts).isEmpty();
+    }
 }