Tool Parameters

Parameters define what information your tool needs and what it returns. Well-defined parameters help the AI use your tools correctly.

Defining Parameters

Each parameter has:

Property	Description
Name	Parameter identifier (no spaces)
Type	Data type (string, number, boolean, etc.)
Required	Whether it must be provided
Description	What the parameter is for
Default	Default value if not provided

Parameter Types

String

Text values:

Name: city
Type: string
Required: true
Description: "City name to look up"

Number

Numeric values:

Name: limit
Type: number
Required: false
Default: 10
Description: "Maximum results to return"

Boolean

True/false:

Name: include_details
Type: boolean
Required: false
Default: false
Description: "Include extra details in response"

Array

List of values:

Name: tags
Type: array
Items: string
Description: "List of tags to filter by"

Object

Structured data:

Name: filters
Type: object
Properties:
  status: string
  priority: number
Description: "Filter criteria"

Writing Good Descriptions

Descriptions help the AI understand when and how to use parameters.

Good descriptions:

"City name to check weather for (e.g., 'New York', 'London')"
"Maximum number of results, between 1 and 100"
"Date in YYYY-MM-DD format"

Bad descriptions:

"The city"
"Number"
"Input value"

Validation

Required vs Optional

Mark parameters required only if the tool cannot function without them.

# Required - tool can't work without this
city (string, required): "City name"

# Optional - has sensible default
units (string, optional, default: "metric"): "Temperature units"

Value Constraints

Document constraints in the description:

limit (number, required): "Results to return, 1-100"
status (string, required): "Order status: pending, shipped, or delivered"

Example: Search Tool

Tool: Search Products

Parameters:
  query (string, required):
    "Search query - product name, category, or keywords"

  category (string, optional):
    "Filter by category: electronics, clothing, home, or all"
    Default: "all"

  min_price (number, optional):
    "Minimum price in dollars"

  max_price (number, optional):
    "Maximum price in dollars"

  sort_by (string, optional):
    "Sort results: relevance, price_low, price_high, newest"
    Default: "relevance"

  limit (number, optional):
    "Maximum results, 1-50"
    Default: 10

Using Parameters in Tools

In API Tools

Reference in URL or body:

Endpoint: https://api.example.com/search?q={{query}}&limit={{limit}}

Body:
{
  "search": "{{query}}",
  "filters": {
    "category": "{{category}}",
    "min_price": {{min_price}},
    "max_price": {{max_price}}
  }
}

In Code Tools

Access via params object:

const query = params.query;
const limit = params.limit || 10;
const minPrice = params.min_price || 0;

// Use parameters in logic...

Output Definition

Define what your tool returns:

Returns:
  results (array): List of matching products
  total_count (number): Total matches found
  query_time_ms (number): Search duration

Clear output definitions help the AI present results to users.