Problem Defining Tools with Optional Input Parameters

[jasontjahjono]

Hi i'm trying to create a tool-calling agent in Langgraph typescript. I've defined the agent, tool, and tool input schema as follows:

Tool Schema:

export const ToolSchema = {
  roomRecommendation: z.object({
    view: z
      .enum(['Ocean', 'Resort', 'Forest', 'unspecified'])
      .optional()
      .describe(
        'The view of the room. Valid options: Ocean, Resort, Forest. Optional field, return "unspecified" if not specified.',
      )
      .default('unspecified'),
  }),
};

Tool:

tool(
    async ({
      view = 'unspecified',
    }) => {
      // Implement room recommendation logic here
      // Must return a string
      console.log(view);
      return JSON.stringify({
        recommendedRooms: [
          // room recommendations based on params
        ],
      });
    },
    {
      name: 'roomRecommendation',
      description:
        'Recommends hotel rooms based on guest requirements and preferences. The view parameter defaults to "unspecified" if not provided. DO NOT ask the user about view if they do not specify it.',
      schema: ToolSchema.roomRecommendation,
    },
  ),

I also prompted the agent to default to unspecified if user does not specify an optional field.

The problem is that every time a user prompts: "i wanna book a room", the agent always returns an AIMessage "do you have any view preference (Ocean, Forest, Resort)" instead of defaulting to "unspecified".

How do I implement optional input params for tools correctly? Thank you