From 277391a389496222556db45ee0f2ef8ad430f29c Mon Sep 17 00:00:00 2001
From: Paul Silvis <paulsilvis@gmail.com>
Date: Sun, 2 Nov 2025 09:43:29 -0800
Subject: [PATCH] fix(google): Fixes Gemini API parse issue by converting
 nullable type arrays to single types in tool schemas

Fixes issue where Gemini API rejected tool schemas containing type arrays
like ["string", "null"]. Gemini's API expects type fields to be single
string values, not arrays.

The root cause was in the process_map function, which was cloning values
for most keys instead of calling process_value. The process_value function
already had logic to convert type arrays to single values, but it was only
being called for specific keys (properties, items, anyOf, allOf), not for
the type key itself.

This fix changes the default case in process_map to call process_value,
which properly converts type arrays like ["string", "null"] to "string"
(extracting the non-null type).

Signed-off-by: Paul Silvis <paulsilvis@gmail.com>
---
 crates/goose/src/providers/formats/google.rs | 34 +++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/crates/goose/src/providers/formats/google.rs b/crates/goose/src/providers/formats/google.rs
index 7fd1dd075197..786762328b15 100644
--- a/crates/goose/src/providers/formats/google.rs
+++ b/crates/goose/src/providers/formats/google.rs
@@ -238,7 +238,7 @@ pub fn process_map(map: &Map<String, Value>, parent_key: Option<&str>) -> Value
                         value.clone()
                     }
                 }
-                _ => value.clone(),
+                _ => process_value(value, Some(key.as_str())),
             };
 
             Some((key.clone(), processed_value))
@@ -858,4 +858,36 @@ mod tests {
 
         assert_eq!(payload, expected_payload);
     }
+
+    #[test]
+    fn test_tools_with_nullable_types_converted_to_single_type() {
+        // Test that type arrays like ["string", "null"] are converted to single types
+        let params = object!({
+            "properties": {
+                "nullable_field": {
+                    "type": ["string", "null"],
+                    "description": "A nullable string field"
+                },
+                "regular_field": {
+                    "type": "number",
+                    "description": "A regular number field"
+                }
+            }
+        });
+        let tools = vec![Tool::new("test_tool", "test description", params)];
+        let result = format_tools(&tools);
+
+        assert_eq!(result.len(), 1);
+        assert_eq!(result[0]["name"], "test_tool");
+
+        // Verify that the type array was converted to a single string type
+        let nullable_field = &result[0]["parameters"]["properties"]["nullable_field"];
+        assert_eq!(nullable_field["type"], "string");
+        assert_eq!(nullable_field["description"], "A nullable string field");
+
+        // Verify that regular types are unchanged
+        let regular_field = &result[0]["parameters"]["properties"]["regular_field"];
+        assert_eq!(regular_field["type"], "number");
+        assert_eq!(regular_field["description"], "A regular number field");
+    }
 }