fix: disable strict mode for MCP tools to preserve optional parameters

daniel-lxs · daniel-lxs · commit 60f5d67e37b4 · 2025-12-19T15:50:46.000-05:00
MCP tools (like Linear's MCP server) have optional parameters that were broken
by OpenAI's strict mode which requires ALL properties to be in the required array.

This change:
- Checks if tool name starts with 'mcp--' prefix
- Sets strict: false for MCP tools
- Preserves original schema without forcing all properties to required

Fixes ROO-241
diff --git a/src/api/providers/base-provider.ts b/src/api/providers/base-provider.ts
@@ -28,18 +28,26 @@ export abstract class BaseProvider implements ApiHandler {
 			return undefined
 		}
 
-		return tools.map((tool) =>
-			tool.type === "function"
-				? {
-						...tool,
-						function: {
-							...tool.function,
-							strict: true,
-							parameters: this.convertToolSchemaForOpenAI(tool.function.parameters),
-						},
-					}
-				: tool,
-		)
+		return tools.map((tool) => {
+			if (tool.type !== "function") {
+				return tool
+			}
+
+			// MCP tools use the 'mcp--' prefix - disable strict mode for them
+			// to preserve optional parameters from the MCP server schema
+			const isMcpTool = tool.function.name.startsWith("mcp--")
+
+			return {
+				...tool,
+				function: {
+					...tool.function,
+					strict: !isMcpTool,
+					parameters: isMcpTool
+						? tool.function.parameters
+						: this.convertToolSchemaForOpenAI(tool.function.parameters),
+				},
+			}
+		})
 	}
 
 	/**
diff --git a/src/api/providers/openai-native.ts b/src/api/providers/openai-native.ts
@@ -291,13 +291,20 @@ export class OpenAiNativeHandler extends BaseProvider implements SingleCompletio
 			...(metadata?.tools && {
 				tools: metadata.tools
 					.filter((tool) => tool.type === "function")
-					.map((tool) => ({
-						type: "function",
-						name: tool.function.name,
-						description: tool.function.description,
-						parameters: ensureAllRequired(tool.function.parameters),
-						strict: true,
-					})),
+					.map((tool) => {
+						// MCP tools use the 'mcp--' prefix - disable strict mode for them
+						// to preserve optional parameters from the MCP server schema
+						const isMcpTool = tool.function.name.startsWith("mcp--")
+						return {
+							type: "function",
+							name: tool.function.name,
+							description: tool.function.description,
+							parameters: isMcpTool
+								? tool.function.parameters
+								: ensureAllRequired(tool.function.parameters),
+							strict: !isMcpTool,
+						}
+					}),
 			}),
 			...(metadata?.tool_choice && { tool_choice: metadata.tool_choice }),
 		}
