🤖 LangChain Agent with Gmail Integration

An AI-powered agent built using LangChain, OpenAI, and Gmail API that can dynamically invoke tools based on user requests.

---

🚀 Features

🌤️ Weather Tool

Retrieve weather information for a specified city.

Example

What is the weather in Hyderabad?

---

📰 Post Retrieval Tool

Fetch post details from JSONPlaceholder using a Post ID.

Example

Get post 20

API:

https://jsonplaceholder.typicode.com/posts/{id}

---

💡 Daily Motivational Thought generator

Uses the OpenAI language model to generate a short, inspirational thought that can provide daily motivation and encouragement. .

Example

Generate today's thought

---

📧 Gmail Subject Retrieval Tool

Connects securely to Gmail using OAuth 2.0 and retrieves the latest email subjects from the user's Primary Inbox.

Example

Show my latest 2 email subjects

---

🏗️ Architecture

                 ┌─────────────┐
                 │    User     │
                 └──────┬──────┘
                        │
                        ▼
              ┌──────────────────┐
              │ LangChain Agent  │
              └────────┬─────────┘
                       │
                       ▼
               ┌─────────────┐
               │ OpenAI LLM  │
               └──────┬──────┘
                      │
      ┌───────────────┼────────────────┐
      │               │                │
      ▼               ▼                ▼

🌤️ Weather     📰 Posts      📧 Gmail Tool

      │               │                │
      ▼               ▼                ▼

 External API   JSONPlaceholder   Gmail API

                      │
                      ▼

              Final AI Response

---

🛠️ Tech Stack

Technology	Purpose
🐍 Python	Core Programming Language
🦜 LangChain	Agent Framework
🕸️ LangGraph	Agent Execution Engine
🤖 OpenAI API	LLM Integration
📧 Gmail API	Email Retrieval
🔐 OAuth 2.0	Authentication
🌐 Requests	HTTP Requests
⚙️ Python Dotenv	Environment Variables

---

📦 Installation

Install required packages:

pip install langchain
pip install langchain-openai
pip install langgraph
pip install python-dotenv
pip install requests
pip install google-api-python-client
pip install google-auth-oauthlib
pip install google-auth-httplib2

---

🔑 Environment Setup

Create a .env file:

OPENAI_API_KEY=your_openai_api_key

---

📧 Gmail API Setup

Step 1

Create a Google Cloud Project.

Step 2

Enable Gmail API.

Step 3

Configure OAuth Consent Screen.

Step 4

Create OAuth Client ID.

Select:

Desktop Application

Step 5

Download credentials file.

Rename to:

credentials.json

Project Structure:

project/
│
├── dynamic_agent_input.py
├── credentials.json
├── .env
├── token.json
└── README.md

---

🔐 Authentication Flow

User
 ↓
Google Login
 ↓
OAuth Consent
 ↓
Access Granted
 ↓
token.json Generated
 ↓
Gmail API Access

First run requires login.

Subsequent runs use the stored token.

---

▶️ Running the Agent

Fetch Post

python dynamic_agent_input.py "Get post 20"

Generate Thought

python dynamic_agent_input.py "Generate a daily thought"

Gmail Subjects

python dynamic_agent_input.py "Show my latest email subjects"

---

📊 Agent Execution Flow

User Query
     ↓
LangChain Agent
     ↓
OpenAI Model
     ↓
Tool Selection
     ↓
Tool Execution
     ↓
External API
     ↓
Tool Result
     ↓
LLM Formatting
     ↓
Final Response

---

⚠️ Security Best Practices

Never commit:

credentials.json
token.json
.env

Add to .gitignore:

credentials.json
token.json
.env
__pycache__/
venv/

---

📚 Concepts Demonstrated

✅ Tool Calling

✅ Agent Architecture

✅ OAuth 2.0 Authentication

✅ Gmail API Integration

✅ OpenAI Integration

✅ External API Consumption

✅ Dynamic Workflow Execution

✅ LangChain Agent Development

---

🎯 Future Enhancements

• 📩 Email Summarization
• ✉️ Email Draft Generation
• 📅 Calendar Integration
• 🌦️ Real Weather API Integration
• 🗄️ Database Connectivity
• 🔎 Multi-Tool Agent Workflows

---

👨‍💻 Author

Sathvik Chekkali

Built for learning Agentic AI, LangChain, Tool Calling, and External API Integration.