Appian DEV MCP 26.6.100 saves Any Type / Variant test output type as Expression

I tested the option to create test cases in an expression rule using Appian DEV MCP. The test case output type should be “Any Type” and the expected value is a Map.

I identified multiple issues:

1. The AI agent (Claude) executed createExpressionRuleTestCase and updateExpressionRuleTestCase tools - the expectedOutputType was saved as Expression.

When I look at the test in Designer it is displayed as on picture below. The test fails in designer. I can click on the Clear link (next to the value) to reset the value. When I paste the value displayed here, it is accepted by Appian designer as valid and the test pass.

2.  runAllExpressionRuleTestCases fails correct Any Type tests with EXPECTED_OUTPUT_TYPE.

I created a test case manually in designer (and it pass).

When AI agent executed runAllExpressionRuleTestCase, the MCP reported the test case as failed. 

This is the line from the run:

"name": "Test case 4: Map",
"success": false,
"testErrors": [{"type": "EXPECTED_OUTPUT_TYPE",
                "details": "Test output type did not match asserted type"}]

• EXPECTED_OUTPUT_TYPE is the error code the runner gave. It means "the result has a different type than the test expects".
• My test says the expected output is of type Any Type.
• The rule returns a Map.
• Any Type should accept any result, including a Map, which is why the test passes in Designer.
• The MCP runner seems to read "Any Type" as one specific type, sees that a Map isn't that type, and fails the test.

The values themselves weren't compared at all; it failed on the type check alone.

3. Both createExpressionRuleTestCases and createExpressionRuleTestCase ignore the type of each test input: "type": "Text" is saved as null. Tests created in Designer on the same rule show "type": "Text". No effect on running the tests has been seen so far.