From e7649e0151f4296b53596cb1f99cc9cf7305a928 Mon Sep 17 00:00:00 2001
From: Frank <97429702+tsubasakong@users.noreply.github.com>
Date: Thu, 12 Mar 2026 10:55:06 -0700
Subject: [PATCH] fix: add fallback Gemini array item schema

---
 astrbot/core/agent/tool.py            | 12 ++++++-
 tests/unit/test_tool_google_schema.py | 47 +++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)
 create mode 100644 tests/unit/test_tool_google_schema.py

diff --git a/astrbot/core/agent/tool.py b/astrbot/core/agent/tool.py
index c2536708e6..a7707c9a6f 100644
--- a/astrbot/core/agent/tool.py
+++ b/astrbot/core/agent/tool.py
@@ -293,7 +293,17 @@ def convert_schema(schema: dict) -> dict:
                 if properties:
                     result["properties"] = properties
 
-            if "items" in schema:
+            if target_type == "array":
+                # Gemini rejects array schemas that omit `items`, while JSON Schema
+                # producers in the wild (especially external MCP tools) sometimes
+                # leave element types unspecified. Fall back to a permissive string
+                # item schema so tool calling stays functional instead of failing the
+                # whole request with `items: missing field`.
+                if isinstance(schema.get("items"), dict) and schema["items"]:
+                    result["items"] = convert_schema(schema["items"])
+                else:
+                    result["items"] = {"type": "string"}
+            elif "items" in schema:
                 result["items"] = convert_schema(schema["items"])
 
             return result
diff --git a/tests/unit/test_tool_google_schema.py b/tests/unit/test_tool_google_schema.py
new file mode 100644
index 0000000000..eed2311163
--- /dev/null
+++ b/tests/unit/test_tool_google_schema.py
@@ -0,0 +1,47 @@
+from astrbot.core.agent.tool import FunctionTool, ToolSet
+
+
+def test_google_schema_adds_default_items_for_array_parameters_without_items():
+    tool = FunctionTool(
+        name="lookup_sources",
+        description="Look up sources by UUID.",
+        parameters={
+            "type": "object",
+            "properties": {
+                "source_uuids": {
+                    "type": "array",
+                    "description": "Source UUIDs to fetch.",
+                }
+            },
+        },
+    )
+
+    schema = ToolSet(tools=[tool]).google_schema()
+    source_uuids = schema["function_declarations"][0]["parameters"]["properties"][
+        "source_uuids"
+    ]
+
+    assert source_uuids["type"] == "array"
+    assert source_uuids["items"] == {"type": "string"}
+
+
+def test_google_schema_preserves_explicit_array_item_schema():
+    tool = FunctionTool(
+        name="lookup_numbers",
+        description="Look up integer values.",
+        parameters={
+            "type": "object",
+            "properties": {
+                "numbers": {
+                    "type": "array",
+                    "items": {"type": "integer", "format": "int32"},
+                }
+            },
+        },
+    )
+
+    schema = ToolSet(tools=[tool]).google_schema()
+    numbers = schema["function_declarations"][0]["parameters"]["properties"]["numbers"]
+
+    assert numbers["type"] == "array"
+    assert numbers["items"] == {"type": "integer", "format": "int32"}