---
title: Tool Calls & Approvals
description: Understand tool availability, execution, results, and approval requests
---

Tools let a conversation perform operations such as search, document editing, and code execution. EVE runs the native tool definitions and records their results. ChatJS composes the available definitions and their client renderers.

## Installation and availability

Installing a tool adds its source and registration. Runtime availability also depends on its declared requirements, the session, and the selected model's capabilities. Installation alone does not make every tool available to every conversation. Guest Chat uses a fixed model without tools or files.

Tools have their own catalog and installation contract. [MCP](../plugins/mcp) is a plugin that connects external tools. Gateways, storage, and sandboxes provide infrastructure used by tools and the runtime.

## Execution and rendering

A tool call has validated input, execution, and a result. Server implementation stays separate from browser rendering so provider credentials do not enter the client bundle. Tool renderers display execution state and output in the conversation.

See [Creating Tools](../tools/authoring) for native definitions and renderers, or [Custom Tool Part](../cookbook/tool-part) for a rendering walkthrough.

## Approval

A tool can require native approval before execution. The interface presents the request and sends the user's decision back to EVE. A chat message saying “yes” is not a substitute for the tool's approval receipt.

For example, [document deletion](../tools/canvas#document-deletion-with-approval) requests the owner's approval for an exact title and revision. Rejection leaves the document unchanged. Changes made before approval can invalidate the request. MCP applies its connector approval policy to external tools.

Approval does not replace authorization or input validation. The tool still checks the caller and the current resource when executing.

## Choose and extend tools

Use [Installing Tools](../tools/install) to add a capability and [Explicit Tool Selection](../cookbook/explicit-tool-selection) to customize selection. See [Execution & Recovery](./execution) for cancellation and reconnecting.