Defining tool schemas and descriptions in Agentic AI

Introduction

Defining tool schemas and descriptions helps AI agents understand what tools they can use and how to use them correctly.

When building an AI agent that needs to interact with multiple tools or APIs.

When you want the AI to know what inputs a tool requires and what outputs it produces.

When you want to make your AI system more organized and easier to maintain.

When you want to improve the AI's ability to choose the right tool for a task.

When you want to provide clear documentation for tools used by AI agents.

Syntax

Agentic AI

tool_schema = {
    "name": "tool_name",
    "description": "What the tool does",
    "parameters": {
        "param1": "description of param1",
        "param2": "description of param2"
    }
}

The schema is usually a dictionary or JSON object describing the tool.

Descriptions should be clear and simple so the AI can understand the tool's purpose.

Examples

This schema describes a calculator tool with operation type and numbers as inputs.

Agentic AI

tool_schema = {
    "name": "calculator",
    "description": "Performs basic math operations",
    "parameters": {
        "operation": "Type of math operation like add or subtract",
        "numbers": "List of numbers to calculate"
    }
}

This schema defines a weather API tool with location and units parameters.

Agentic AI

tool_schema = {
    "name": "weather_api",
    "description": "Fetches current weather data",
    "parameters": {
        "location": "City or coordinates for weather data",
        "units": "Measurement units like metric or imperial"
    }
}

Sample Model

This program defines a function to create tool schemas and uses it to define a text summarizer tool schema. It then prints the schema.

Agentic AI

def define_tool_schema(name, description, parameters):
    return {
        "name": name,
        "description": description,
        "parameters": parameters
    }

# Define a tool schema for a text summarizer
text_summarizer_schema = define_tool_schema(
    "text_summarizer",
    "Summarizes long text into short key points",
    {
        "text": "The input text to summarize",
        "max_length": "Maximum length of the summary"
    }
)

print(text_summarizer_schema)

Important Notes

Always keep tool descriptions simple and clear for better AI understanding.

Include all necessary parameters so the AI knows what inputs to provide.

Use consistent naming to avoid confusion when multiple tools are used.

Summary

Tool schemas describe what a tool does and what inputs it needs.

Clear descriptions help AI agents use tools correctly.

Defining schemas makes AI systems easier to build and maintain.

Practice

1. What is the main purpose of defining a tool schema in agentic AI?

easy

A. To describe what the tool does and what inputs it needs

B. To write the tool's source code

C. To train the AI model

D. To store user data securely

Solution

1. Step 1: Understand the role of tool schemas

   Tool schemas explain what a tool does and what inputs it requires for proper use.

2. Step 2: Differentiate from other tasks

   Writing code, training models, or storing data are separate tasks not covered by schemas.

3. Final Answer:

   To describe what the tool does and what inputs it needs -> Option A

4. Quick Check:

   Tool schema = tool description + inputs [OK]

Hint: Schemas explain tool purpose and inputs clearly [OK]

Common Mistakes:

• Confusing schema with code implementation
• Thinking schema trains the AI
• Assuming schema stores data

2. Which of the following is the correct way to define a tool schema description in JSON format?

easy

A. {"name": search, "desc": "Finds info", inputs: {query: string}}

B. {"tool": search, description: Finds info, inputs: query string}

C. {"name": "search", "description": "Finds information", "inputs": {"query": "string"}}

D. {name: "search", description: "Finds information", inputs: {query: string}}

Solution

1. Step 1: Check JSON syntax correctness

   {"name": "search", "description": "Finds information", "inputs": {"query": "string"}} uses proper JSON with keys and string values quoted correctly.

2. Step 2: Verify key names and structure

   {"name": "search", "description": "Finds information", "inputs": {"query": "string"}} uses "name", "description", and "inputs" keys properly with correct value types.

3. Final Answer:

   {"name": "search", "description": "Finds information", "inputs": {"query": "string"}} -> Option C

4. Quick Check:

   Valid JSON with quoted keys and strings = {"name": "search", "description": "Finds information", "inputs": {"query": "string"}} [OK]

Hint: Look for quoted keys and string values in JSON [OK]

Common Mistakes:

• Missing quotes around keys or strings
• Using unquoted identifiers
• Incorrect key names or structure

3. Given this tool schema snippet:

{"name": "calculator", "description": "Performs math operations", "inputs": {"operation": "string", "x": "number", "y": "number"}}

What would be the expected output if the tool is called with inputs {"operation": "add", "x": 5, "y": 3}?

medium

A. 8

B. "add"

C. 53

D. Error: missing inputs

Solution

1. Step 1: Understand the tool schema inputs

   The tool expects an operation (like add) and two numbers x and y.

2. Step 2: Apply the operation to inputs

   Adding 5 and 3 results in 8 as output.

3. Final Answer:

   8 -> Option A

4. Quick Check:

   5 + 3 = 8 [OK]

Hint: Match inputs to operation and compute result [OK]

Common Mistakes:

• Returning operation string instead of result
• Concatenating numbers as strings
• Assuming missing inputs cause error

4. You have this tool schema:

{"name": "translator", "description": "Translates text", "inputs": {"text": "string", "target_lang": "string"}}

Which error is present in this schema?

medium

A. Description is too long

B. Name key is missing

C. Input types should be numbers

D. Missing closing brace for inputs object

Solution

1. Step 1: Check JSON syntax carefully

   The inputs object is opened but not closed with a } before the schema ends.

2. Step 2: Verify other keys

   Name key exists, description length is fine, input types as strings are correct.

3. Final Answer:

   Missing closing brace for inputs object -> Option D

4. Quick Check:

   Unclosed braces cause JSON errors [OK]

Hint: Count opening and closing braces carefully [OK]

Common Mistakes:

• Ignoring missing braces
• Thinking input types must be numbers
• Assuming description length matters

5. You want to define a tool schema for a weather forecast tool that takes a city name and date, and returns temperature and conditions. Which schema correctly describes this tool?

hard

A. {"name": "weather", "description": "Forecast tool", "inputs": {"city": "string"}, "outputs": {"temp": "string", "cond": "string"}}

B. {"name": "weather", "description": "Provides weather forecast", "inputs": {"city": "string", "date": "string"}, "outputs": {"temperature": "number", "conditions": "string"}}

C. {"name": "weather", "description": "Gives weather", "inputs": {"location": "string", "day": "date"}}

D. {"name": "weather", "inputs": {"city": "string", "date": "string"}}

Solution

1. Step 1: Check completeness of schema

   {"name": "weather", "description": "Provides weather forecast", "inputs": {"city": "string", "date": "string"}, "outputs": {"temperature": "number", "conditions": "string"}} includes name, description, inputs (city and date), and outputs (temperature and conditions) as required.

2. Step 2: Verify input and output types

   Inputs are strings (city, date), outputs are number and string, matching expected data.

3. Final Answer:

   {"name": "weather", "description": "Provides weather forecast", "inputs": {"city": "string", "date": "string"}, "outputs": {"temperature": "number", "conditions": "string"}} -> Option B

4. Quick Check:

   Complete schema with inputs and outputs = {"name": "weather", "description": "Provides weather forecast", "inputs": {"city": "string", "date": "string"}, "outputs": {"temperature": "number", "conditions": "string"}} [OK]

Hint: Include inputs and outputs with correct types [OK]

Common Mistakes:

• Omitting outputs section
• Using wrong input/output keys or types
• Leaving out description