Connect a tool to a prompt

What you'll build: a prompt that calls a tool from the catalog, one of its aliases calling a different build of that same tool, and a look at the tool's audit trail to see when its code last changed underneath you.

This picks up where Create a tool leaves off. That guide puts the tool in the catalog; this one decides which build of it each of your prompt's aliases calls. Running it is the step after, in Call a prompt's tools from the SDK.

How a binding works

A binding is the connection between a prompt and a tool. It stores the tool alias to follow — production, staging, whatever the tool has — and resolves it at call time. Moving the tool's own alias to a newer version changes what runs, with no change on the prompt side.

Bindings hang off the prompt's aliases, not its versions. A prompt version is the template and nothing else. That means connecting a tool is a single write that takes effect on the next call: there is no version to commit and no alias to promote afterwards.

Each prompt alias either has its own binding for a tool or inherits the prompt's default binding. So a cell in the Tools tab's grid reads one of four ways:

Cell reads	Meaning
production → v3	this alias follows the tool's production alias, which currently points at v3
pinned to v2	this alias is locked to tool version 2 — no alias move reaches it
same as default	no binding of its own; the default column applies
not used here	this alias deliberately does not call the tool, even though the default does
not connected	the prompt does not call this tool at all

not used here exists because an empty cell already means same as default. It is how you keep a billing call out of staging while production keeps it.

1. Connect the tool

Open the prompt, go to its Tools tab, and choose + Connect a tool from the catalog.

The tool lands in the default column, following its own production alias. Every prompt alias inherits that immediately — the column header counts them ("3 aliases inheriting"), and the aliases themselves are listed as pills under Following the default.

That is the whole common case. One row, one cell, done.

To change what the default follows, click the cell. The dropdown groups its options: every alias the tool has under Follow an alias — moves when it is promoted, every version number under Pin a version — never moves, and, on an alias column, Not for this alias under Stop calling it. A pin is the stronger promise: it never moves, so a tool commit or an alias move cannot reach it.

2. Give one alias its own tools

The alias pills under Following the default are the control: click one and that alias gets a column of its own. Its cells start on same as default; set one and only that alias changes. The pill disappears from the list as it moves into the grid.

This is how a tool gets rolled out or retired. Point staging at the tool's staging alias so it runs the build with your fix in it, while production keeps running the tested one. Or pick Not for this alias under Stop calling it, for a tool a test run must never call.

The two alias names are independent. Binding the prompt's production to the tool's staging alias is exactly as valid as binding it to production — they are different namespaces that happen to reuse the same words.

Two ways back to the default: pick Go back to the default in one cell, or use the column's × to reset that alias in full.

The column header shows the prompt version, not the tool version

Under a customised alias's name you'll see serving v2. That is the prompt version this alias currently serves — its template. It has no bearing on which tools the alias calls.

3. Check what a call will actually use

Rendering the prompt reports its resolved tools. tools holds the OpenAI-shaped definitions, and toolResolutions sits beside it — one entry per tool, same order — naming the alias or pin that resolved, the tool version it landed on, and whether the binding came from this prompt alias (source: "alias") or was inherited from the default (source: "default").

{
  "toolResolutions": [
    { "name": "get_weather", "alias": "staging", "versionNumber": 1, "source": "alias" }
  ]
}

4. See when the tool's own code changed

A tool's Audit tab lists every version commit — including ones a code push created via sync — and every binding set or removed against it:

The code sync badge marks a version created by a code push (POST /api/v1/tools/:id/sync detecting the function's code changed), as opposed to a manual commit from the dashboard or API. This is how an admin notices a tool changed underneath an alias a prompt is relying on, without having to compare the Versions tab against memory.

Doing this over the API

curl

# The default binding — every prompt alias inherits it
curl -X PUT "$ACRUXCORE_BASE_URL/prompts/<prompt-id>/tools/<tool-id>" \
  -H "Authorization: Bearer $ACRUXCORE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"tool_alias":"production"}'

# One alias's own binding: staging follows the tool's staging alias instead
curl -X PUT "$ACRUXCORE_BASE_URL/prompts/<prompt-id>/aliases/staging/tools/<tool-id>" \
  -H "Authorization: Bearer $ACRUXCORE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"tool_alias":"staging"}'

# Read the whole picture: the default, plus every alias and whether it is customised
curl "$ACRUXCORE_BASE_URL/prompts/<prompt-id>/tools" \
  -H "Authorization: Bearer $ACRUXCORE_API_KEY"

# Render reports what resolved, and which binding decided it
curl -X POST "$ACRUXCORE_BASE_URL/prompts/weather-brief/staging/render" \
  -H "Authorization: Bearer $ACRUXCORE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"variables":{"city":"Lisbon"}}'

{
  "toolResolutions": [
    {"name":"get_weather","alias":"staging","versionNumber":1,"source":"alias"}
  ]
}

Node (SDK)

import AcruxCore, { withToolOverride } from '@acruxcoreai/sdk';

const hub = new AcruxCore();
const rendered = await hub.prompts.render('weather-brief', 'staging', { city: 'Lisbon' });

// rendered.toolResolutions[0] — { name: 'get_weather', alias: 'staging', versionNumber: 1, source: 'alias' }

// One-off swap for this call only — warns, naming the binding actually configured
// on the prompt, so you don't mistake a one-off for the standing setup.
const { tools, toolRefs } = withToolOverride(rendered, { name: 'get_weather', alias: 'production' });

Python (SDK)

from acruxcore import AcruxCore, with_tool_override

hub = AcruxCore()
rendered = await hub.prompts.render("weather-brief", "staging", {"city": "Lisbon"})

# rendered.tool_resolutions[0] — ToolResolution(name='get_weather', alias='staging', version_number=1, source='alias')

result = with_tool_override(rendered, name="get_weather", alias="production")

Every binding write needs an owner, admin, or editor role. tool_alias must already exist on the tool, and pinned_version_number must be a version it has — both are checked at write time, so a typo fails with VALIDATION_ERROR there rather than surfacing on a later call. Full reference: Prompt Tool Bindings and Audit in the API Reference.

What's next

• Call a prompt's tools from the SDK — run the tool you just bound, streaming or not.
• Create a tool — where the tool this guide binds came from.
• Version and track a tool — move the alias a binding follows, and read what the tool actually cost.