fix: address PR feedback

- Update intro text with links to filesystem, commands, and firewall
- Add link to custom templates in Note section
- Change description to "Secure runtime environments for AI agents"

Author: beran-t

docs/sandbox.mdx

@@ -1,10 +1,12 @@
 ---
 title: "Sandbox overview"
 sidebarTitle: Overview
-description: "Isolated cloud environments for running AI-generated code"
+description: "Secure runtime environments for AI agents"
 ---
 
-A sandbox is an isolated cloud VM that starts in **~100ms**. Each sandbox has its own filesystem, can run processes, and has internet access. Sandboxes are designed to run AI-generated code safely.
+A sandbox is an agentic runtime which is an isolated cloud VM under the hood. Sandboxes can start in as little as **~100ms**. Each sandbox has its own [filesystem](/docs/filesystem), can start [processes](/docs/commands), and has internet access with [configurable firewall](/docs/sandbox/internet-access#fine-grained-network-control).
+
+Sandboxes are designed to run thousands of AI agents safely with access to the real-world tools as on your own computer.
 
 <CodeGroup>
 ```js JavaScript & TypeScript
@@ -52,7 +54,7 @@ sbx.kill()
 | Internet | Enabled |
 
 <Note>
-These are defaults for the [code-interpreter](https://github.com/e2b-dev/code-interpreter) template. Custom templates can have different CPU/RAM configurations.
+These are defaults for the [code-interpreter](https://github.com/e2b-dev/code-interpreter) template. [Custom templates](/docs/template/quickstart) can have different CPU/RAM configurations.
 </Note>
 
 See [lifecycle](/docs/sandbox/lifecycle) for timeout configuration.