---
title: "Lifecycle & capability registration · Finch Agent"
description: "The full lifecycle, static declaration vs. dynamic registration, and capability cooperation"
source: https://finchwork.app/en/docs/minitools-lifecycle
---

# Lifecycle & capability registration

## Full lifecycle

## Static declaration vs. dynamic registration

Capability registration in Finch is generally two-phase: the manifest declares a slot, and code fills in the behavior.

|  | Static manifest declaration | Dynamic registration in `activate()` |
| --- | --- | --- |
| Determines | Whether a button/container **exists**, its icon, its tooltip | The badge text, menu contents, click behavior |
| Read when | At install and startup | On-demand, during user interaction |
| Can it hide | The declared slot always remains | `getBadge()` can throw to hide the button |

This design exists because Finch needs to render the UI skeleton before a mini tool is even activated — static declarations keep the UI from flickering.

**Note: `getMenu()` returning an empty array doesn't make the button disappear.** Visibility is controlled by the manifest.

## Three capability exit points

## Capabilities: how mini tools cooperate

Mini tools never import each other directly — they cooperate through named interfaces. Both the provider and the consumer must declare this in the manifest:

```json
{
  "provides": { "capabilities": ["my.feature"] },
  "requires": { "capabilities": ["mcp.client"] }
}
```

```ts
// Provider
ctx.capabilities.provide('my.feature', {
  async listItems() { return []; },
}, { version: '1.2.0' });

// Consumer
if (ctx.capabilities.has('my.feature')) {
  const feature = ctx.capabilities.get('my.feature');
  const items = await feature.listItems();   // Always async on the consumer side
}
```

Three things to keep in mind:

-   **Every method is async on the consumer side**, since it's routed across processes.
-   **Activation order is not a dependency contract.** The target capability may activate after you do, so poll briefly while waiting (see [MCP integration](/en/docs/minitools-mcp)).
-   **Keep interfaces small and stable**, using `version` to signal changes as they evolve.