fix: add additionalProperties: false to nested MCP tool schemas

src/core/prompts/tools/native-tools/__tests__/mcp_server.spec.ts

@@ -158,8 +158,8 @@ describe("getMcpServerTools", () => {
 		expect(getFunction(result[0]).parameters).toEqual({
 			type: "object",
 			properties: {
-				requiredField: { type: "string" },
-				optionalField: { type: "number" },
+				requiredField: { type: "string", additionalProperties: false },
+				optionalField: { type: "number", additionalProperties: false },
 			},
 			additionalProperties: false,
 			required: ["requiredField"],
@@ -186,7 +186,7 @@ describe("getMcpServerTools", () => {
 		expect(getFunction(result[0]).parameters).toEqual({
 			type: "object",
 			properties: {
-				optionalField: { type: "string" },
+				optionalField: { type: "string", additionalProperties: false },
 			},
 			additionalProperties: false,
 		})

src/core/prompts/tools/native-tools/mcp_server.ts

@@ -1,6 +1,7 @@
 import type OpenAI from "openai"
 import { McpHub } from "../../../../services/mcp/McpHub"
 import { buildMcpToolName } from "../../../../utils/mcp-name"
+import { ToolInputSchema, type JsonSchema } from "../../../../utils/json-schema"
 
 /**
  * Dynamically generates native tool definitions for all enabled tools across connected MCP servers.
@@ -40,30 +41,24 @@ export function getMcpServerTools(mcpHub?: McpHub): OpenAI.Chat.ChatCompletionTo
 			}
 			seenToolNames.add(toolName)
 
-			const originalSchema = tool.inputSchema as Record<string, any> | undefined
-			const toolInputProps = originalSchema?.properties ?? {}
-			const toolInputRequired = (originalSchema?.required ?? []) as string[]
+			const originalSchema = tool.inputSchema as Record<string, unknown> | undefined
 
-			// Build parameters directly from the tool's input schema.
-			// The server_name and tool_name are encoded in the function name itself
-			// (e.g., mcp_serverName_toolName), so they don't need to be in the arguments.
-			const parameters: OpenAI.FunctionParameters = {
-				type: "object",
-				properties: toolInputProps,
-				additionalProperties: false,
-			}
-
-			// Only add required if there are required fields
-			if (toolInputRequired.length > 0) {
-				parameters.required = toolInputRequired
+			// Parse with ToolInputSchema to ensure additionalProperties: false is set recursively
+			let parameters: JsonSchema
+			if (originalSchema) {
+				const result = ToolInputSchema.safeParse(originalSchema)
+				parameters = result.success ? result.data : (originalSchema as JsonSchema)
+			} else {
+				// No schema provided - create a minimal valid schema
+				parameters = ToolInputSchema.parse({ type: "object" })
 			}
 
 			const toolDefinition: OpenAI.Chat.ChatCompletionTool = {
 				type: "function",
 				function: {
 					name: toolName,
 					description: tool.description,
-					parameters: parameters,
+					parameters: parameters as OpenAI.FunctionParameters,
 				},
 			}