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So far this has been a made-up shop with stand-in tools, running on our servers. Next, you’ll run the same agent from your own code, where its tools can reach your own systems.

I already have an agent

Add a registry skill to the agent you already run, and compare its answers with and without it.

I don't have one yet

Keep going on this page and run order-support.
You need an API key for your SDK’s model, and your copy of order-support from Part 1’s step 4. Parts 3 and 4 work on every tab below. Part 5’s evaluate() takes OpenAI Agents SDK agents only, so choose that tab to run Part 5 as written.

Run it in Colab

Nothing to install. Open the notebook for your SDK: OpenAI Agents SDK, Claude Agent SDK, OpenAI SDK or Anthropic API. LangChain has no notebook yet: use the steps below. Add two keys as Colab Secrets (the key icon in its sidebar): your model provider’s key, and DECIMAL_API_KEY, which is filled in here when you’re signed in: Run the notebook. Then skip to step 5.

Or run it on your machine

You need Python 3.10 or later. Pick your SDK in step 1 and the tabs below follow it.
Paste this into Claude Code, Cursor or another coding agent:

1. Install

Then install your tab’s packages, and replace sk-... with your model provider’s key:
decimalai reads .env when it is imported.

2. Save the program

This is the program from Part 1, complete with its four tools. Save it as main.py:

3. Add your DecimalAI key

Add this line to the same .env. It’s filled in when you’re signed in: The tutorial key lasts 30 days. For a project you’ll keep running, create your own key under Settings → API keys and use that instead.

4. Run it

Real output (the model’s wording varies from run to run):
That’s the answer from the end of Part 1, because agent_config("order-support") read your copy from DecimalAI:
  • The skills and prompt are the ones saved on your copy, including the skill you forked. Your code doesn’t list them.
  • fallback= is used only if the agent has no saved prompt, or DecimalAI can’t be reached when the program starts.
  • Your tools are yours. lookup_order reads a dictionary here and your database in your app. The other three stand in for actions the skills call for: they report what they would do and change nothing.
  • Every run is traced: the model calls, your tools’ calls, the skills it opened, and the versions it ran on. Part 4 reads them.
A model can say it did something without doing it, so don’t take its word for an action: Part 5 checks what the tools really returned.

5. Change the fee again

Your fork is on DecimalAI, so you can change it without touching your code.
  1. Open acme-returns-policy and, under Manage it in DecimalAI, click Open copy.
  2. On its Settings tab, in Body (Markdown), change 10% to 5%.
  3. Click Save Changes, then Publish (affects 1 agent). This makes a new version of your copy for your agent. It stays private: nothing goes to the public registry.
Run python main.py again, or run the notebook’s question cell again:
$44.10 became $46.55 and your code didn’t change. agent_config() reads your copy each time a program starts, and a program that stays running picks up a change within about a minute. The wording varies from run to run, and now and then the reply gives the percentage without the amount. If yours does, run it again.
Do step 1 and step 2 in a new folder, then add the four skills: billing-dispute-resolution, account-deletion-verification-policy, diagnostic-triage-questions and acme-returns-policy. No account is needed:
Each one writes the skill’s files to .agents/skills/ and lists it in .decimal/skills.toml. Run python main.py. Real output (the model’s wording varies from run to run):
Nothing here was sent to DecimalAI. The prompt is your fallback= text and the skills are the registry’s originals, so the fee is the original 15%.Don’t add your DecimalAI key to this folder if you forked a skill in Part 1: connecting a project copies its local skills onto your agent, beside your fork. Use a new folder and follow the steps above instead.

Next: 4. See what it did

Read order-support’s traces, change its prompt, and compare runs from before and after.