[BUG] `ConversionUtils.adkToMcpToolType` throws `NoSuchElementException` for a tool declaration without parameters

[SuperCorleone]

Describe the Bug

adkToMcpToolType guards the empty-declaration case but then calls toolDeclaration.get().parameters().get() — an unguarded Optional.get() on parameters(). A declaration that is present but has no parameters (a valid no-argument tool) yields NoSuchElementException. All built-in ADK tools populate parameters, so the library itself never triggers it, but a user-supplied custom tool overriding declaration() without parameters would.

Root Cause

// ConversionUtils.adkToMcpToolType, ~L36
... toolDeclaration.get().parameters().get() ...   // NoSuchElementException when parameters is empty

Suggested Fix

Guard parameters: toolDeclaration.get().parameters().orElse(null) (or build the MCP tool without an input schema when parameters are absent — which is exactly what the failing test expects).

Corresponding Test (generated)

@Test
public void testAdkToMcpToolType_WithNonEmptyDeclarationAndNullSchema_ReturnsToolWithoutInputSchema() {
    // Given
    String toolName = "testTool";
    String toolDescription = "A test tool";

    when(mockBaseTool.name()).thenReturn(toolName);
    when(mockBaseTool.description()).thenReturn(toolDescription);
    when(mockBaseTool.declaration()).thenReturn(Optional.of(mockFunctionDeclaration));
    when(mockFunctionDeclaration.parameters()).thenReturn(Optional.empty());

    // When
    McpSchema.Tool result = conversionUtils.adkToMcpToolType(mockBaseTool);

    // Then
    assertNotNull(result);
    assertEquals(toolName, result.name());
    assertEquals(toolDescription, result.description());
    assertNull(result.inputSchema());
}

Environment

• Project: adk / google-adk (com.google.adk) · upstream: github.com/google/adk-java
• Version: 0.5.1-SNAPSHOT (local) · Commit: <fill SUT commit> · Java 17 · OS macOS

This input was generated by the test case generator TestFusion developed in our STAR lab.

[hemasekhar-p]

Hi @SuperCorleone, Thank you for reporting this issue. I am able to reproduce this issue which you described. Currently this Issue is under review by our team, we will keep you update if any additional information is required. thank you.

[hemasekhar-p]

@krwc, Please have a look into it.