(flink-agents) branch release-0.2 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 release-0.2
in repository https://gitbox.apache.org/repos/asf/flink-agents.git


The following commit(s) were added to refs/heads/release-0.2 by this push:
     new c0425a5e [hotfix][mcp] Skip listPrompts for MCP servers without prompt 
support (#539)
c0425a5e is described below

commit c0425a5edcd4f5e7ee9fdaa2bf5db4e139bb673c
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     | 20 ++++++++++++++++++++
 .../flink/agents/integrations/mcp/MCPServerTest.java | 11 +++++++++++
 2 files changed, 31 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 64e71a32..c927bbd4 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
@@ -41,6 +41,7 @@ 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;
@@ -257,6 +258,21 @@ 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.
      *
@@ -340,6 +356,10 @@ public class MCPServer extends Resource {
      * @return List of MCPPrompt instances
      */
     public List<MCPPrompt> listPrompts() {
+        if (!supportsPrompts()) {
+            return Collections.emptyList();
+        }
+
         McpSyncClient mcpClient = getClient();
         McpSchema.ListPromptsResult promptsResult = mcpClient.listPrompts();
 
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 5fe52bcc..37f0a491 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;
@@ -243,4 +244,14 @@ class MCPServerTest {
         server.close();
         server.close(); // Calling twice should be safe
     }
+
+    @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();
+    }
 }