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How to Connect Any LLM to Any API in Seconds

mercury0100

— 2 min read
How to Connect Any LLM to Any API in Seconds

Invoke Labs | June 2025

Turn your LLM into an agent that can take action — not just talk.

Modern language models like GPT-4.1 are brilliant at reasoning, writing, and planning. But if they can’t take action — if they’re stuck inside a sandbox — they’re just glorified typewriters.

Invoke fixes that. It’s a zero-boilerplate execution layer that lets any LLM call any real-world API with a single line of code.

In this tutorial, we’ll walk through how to:

  • Connect GPT-4.1 (or any LLM) to real APIs
  • Use tools like Google Calendar or Google Places
  • Let the model find services and take action dynamically

By the end, your model won’t just generate plans — it’ll execute them.

🧰 What You’ll Need

Step 1: Install the Invoke Agent

In your terminal:

pip install invoke-agent

This gives you a universal tool interface — a lightweight router that your model can use to call any API.

Step 2: Get Your Invoke API Key

Head to invoke.network and log in (or create a free account).

Then:

  1. Go to the API Key Manager
  2. Create a new key (e.g. “demo”)
  3. Copy it
  4. Set it in your environment:

export INVOKE_API_KEY=your_key_here

Step 3: Copy the Quickstart Template

Visit the Install page and grab the quickstart snippet.

Paste it into a new Python file, like demo.py.

The template includes an example with Google Calendar and Open-Meteo. But you can easily swap in other APIs using the Invoke Catalog.

Step 4: Add the APIs You Want

Let’s say you want to replace Open-Meteo with Google Places.

  1. Go to the catalog
  2. Find Google Places
  3. Copy the tool block
  4. Paste it into your tool list

That’s it. You don’t need to hard-wire anything or write glue code.

Step 5: Run the Agent

python demo.py

Then just start chatting with your LLM.

For example:

“Find me a good Mexican restaurant in Bondi.”

The model will use Google Places to search — and you’ll get structured results instantly.

Then say:

“Create a calendar event for dinner there tomorrow night.”

If you're using Google Calendar, Invoke will trigger an OAuth flow. Authorize once, and the model can use your calendar from then on.

🧠 What Just Happened?

Behind the scenes:

  • The model discovered the tools from your agents.json
  • It filled in the correct parameters
  • Invoke executed the API call and passed the result back

You didn’t write glue code, auth flows, or SDK wrappers. The model handled everything.

🔗 Connect Any LLM. Any API. Instantly.

Invoke works out of the box with:

  • GPT-4 / 4.1
  • Claude 3
  • LangChain, LlamaIndex, and more
  • Any REST API with an agents.json descriptor

No orchestration. No ceremony. Just one tool — and the ability to find more.

🎥 Watch the Full Demo

Want to see it in action? Watch the video here.

🚀 Get Started Now

Create your free account at invoke.network
Explore the full API catalog
Or dive into the docs

Got questions? Feedback? Use cases you want to share?
Drop us a line or hit us up on Twitter/X.

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