Building Autonomous AI Agents with APIs: Architecture, Memory & Planning

Overview #

An AI agent is an autonomous software system that leverages an LLM as its central reasoning engine to formulate plans, observe environments, execute external tools, and iteratively achieve multi-step objectives.

The Core Loop: Perceive → Plan → Act → Observe #

Unlike simple single-turn chatbots, autonomous agents operate in an iterative loop:

1. Goal Setting: User submits an objective (e.g. 'Refactor the authentication module and verify test suites').
2. Decomposition: Model breaks down the task into sequential steps.
3. Tool Execution: Agent invokes external tools (file system reads, terminal commands, database queries).
4. Environment Observation: The agent parses tool output, evaluates errors, and updates its strategy until the goal is achieved.

Short-Term vs. Long-Term Agentic Memory #

Agents require state management across multi-step runs:
• Working Memory: In-context conversational history containing tool call arguments and results.
• Episodic/Long-Term Memory: Vector embeddings in PostgreSQL/pgvector or Pinecone to recall facts across sessions.

Code Example: Agent Tool Execution Loop in Python #

from openai import OpenAI
import json

client = OpenAI(base_url="https://api.apihundred.com/v1", api_key="your_api100_key")

tools = [{
    "type": "function",
    "function": {
        "name": "execute_sql_query",
        "description": "Execute a readonly SQL query on the database",
        "parameters": {
            "type": "object",
            "properties": {"query": {"type": "string"}},
            "required": ["query"]
        }
    }
}]

messages = [{"role": "user", "content": "How many users signed up this week?"}]

# Step 1: Model decides to call the tool
response = client.chat.completions.create(
    model="claude-3-5-sonnet",
    messages=messages,
    tools=tools
)

tool_call = response.choices[0].message.tool_calls[0]
print(f"Agent requested tool: {tool_call.function.name}")

Frequently Asked Questions #

Q: What is an AI agent?

An AI agent is an autonomous software system powered by a foundation model that plans steps, invokes external tools, and iterates based on environment feedback to accomplish goals without constant human intervention.