Without tools, an agent can only talk about what is in its prompt. With them, it can look up a real order, check real stock, and write a real record — mid-sentence, while the customer waits.
When you'd use it #
Order status
"Where is my order?" becomes a real answer from your own system instead of an apology.
Availability
Check stock or a booking slot before the agent promises anything.
Capturing a lead
Write the enquiry into your CRM as it happens, rather than reading it back out of the transcript later.
Defining a tool #
-
Name it for the model, not for you
get_order_statustells the model when to reach for it.tool_2does not. The name and description are how the model decides. -
Describe when to use it
One clear sentence. This is the single biggest factor in whether the tool gets called at the right moment. -
Declare the parameters
What the model must supply, and their types. Keep the list short — every parameter is something the model can get wrong. -
Configure the call
For a REST tool: method, URL, headers and how parameters map into the request. For a database tool: the query and its bindings. -
Attach it to an agent
A tool exists here but is only usable by agents you attach it to.
Keeping it safe #
| Field | What it does |
|---|---|
| Prefer read-only | Most conversational questions need a lookup, not a write. Reserve writes for tools you have watched behave. |
| Scope the credentials | Use a token that can reach only the endpoint the tool needs. |
| Never return more than the answer | Whatever the endpoint returns can end up paraphrased to a customer. Do not hand back the whole record. |
| Test in the playground | Watch which arguments the model actually invents before it does so in front of someone. |
Where to go next #
Agent builder
Persona, model, temperature, tools and the WhatsApp numbers an agent answers on.
Playground
Test an agent against real prompts before a customer ever reaches it.
MCP servers
Connect Model Context Protocol servers to hand an agent a whole external toolset at once.
Audit logs
Every inference an agent made, with status, tokens, latency and the tools it called.