Work around for MCP Gateway schema issue

Signed-off-by: David Gageot <[email protected]>

Author: dgageot

pkg/model/provider/openai/client.go

@@ -338,6 +338,9 @@ func (c *Client) CreateChatCompletionStream(
 				return nil, err
 			}
 
+			// Fix missing item types in arrays
+			parameters = fixSchemaArrayItems(parameters)
+
 			toolsParam[i] = openai.ChatCompletionFunctionTool(shared.FunctionDefinitionParam{
 				Name:        tool.Name,
 				Description: openai.String(tool.Description),
@@ -447,6 +450,9 @@ func (c *Client) CreateResponseStream(
 			// The Response API requires every parameter to be required
 			parameters = makeAllRequired(parameters)
 
+			// Fix missing item types in arrays
+			parameters = fixSchemaArrayItems(parameters)
+
 			toolsParam[i] = responses.ToolUnionParam{
 				OfFunction: &responses.FunctionToolParam{
 					Name:        tool.Name,

pkg/model/provider/openai/schema.go

@@ -1,6 +1,7 @@
 package openai
 
 import (
+	"slices"
 	"sort"
 
 	"github.com/docker/cagent/pkg/tools"
@@ -58,3 +59,40 @@ func makeAllRequired(schema map[string]any) map[string]any {
 	schema["additionalProperties"] = false
 	return schema
 }
+
+// In Docker Desktop 4.52, the MCP Gateway produces an invalid tools shema for `mcp-config-set`.
+func fixSchemaArrayItems(schema map[string]any) map[string]any {
+	propertiesValue, ok := schema["properties"]
+	if !ok {
+		return schema
+	}
+
+	properties, ok := propertiesValue.(map[string]any)
+	if !ok {
+		return schema
+	}
+
+	for _, propValue := range properties {
+		prop, ok := propValue.(map[string]any)
+		if !ok {
+			continue
+		}
+
+		checkForMissingItems := false
+		switch t := prop["type"].(type) {
+		case string:
+			checkForMissingItems = t == "array"
+		case []string:
+			checkForMissingItems = slices.Contains(t, "array")
+		}
+		if !checkForMissingItems {
+			continue
+		}
+
+		if _, ok := prop["items"]; !ok {
+			prop["items"] = map[string]any{"type": "object"}
+		}
+	}
+
+	return schema
+}

pkg/model/provider/openai/schema_test.go

@@ -53,3 +53,61 @@ func TestMakeAllRequired_NilSchema(t *testing.T) {
 	require.NoError(t, err)
 	assert.JSONEq(t, `{"additionalProperties":false,"properties":{},"type":"object","required":[]}`, string(buf))
 }
+
+func TestFixSchemaArrayItems(t *testing.T) {
+	schema := `{
+  "properties": {
+    "arguments": {
+      "description": "Arguments to pass to the tool (can be any valid JSON value)",
+      "type": [
+        "string",
+        "number",
+        "boolean",
+        "object",
+        "array",
+        "null"
+      ]
+    },
+    "name": {
+      "description": "Name of the tool to execute",
+      "type": "string"
+    }
+  },
+  "required": [
+    "name"
+  ],
+  "type": "object"
+}`
+
+	schemaMap := map[string]any{}
+	err := json.Unmarshal([]byte(schema), &schemaMap)
+	require.NoError(t, err)
+
+	updatedSchema := fixSchemaArrayItems(schemaMap)
+	buf, err := json.Marshal(updatedSchema)
+	require.NoError(t, err)
+
+	assert.JSONEq(t, `{
+  "properties": {
+    "arguments": {
+      "description": "Arguments to pass to the tool (can be any valid JSON value)",
+      "type": [
+        "string",
+        "number",
+        "boolean",
+        "object",
+        "array",
+        "null"
+      ]
+    },
+    "name": {
+      "description": "Name of the tool to execute",
+      "type": "string"
+    }
+  },
+  "required": [
+    "name"
+  ],
+  "type": "object"
+}`, string(buf))
+}