# Activation Reference

4 min read

This page is the single place to look for the question _"why is engine/reader X (not) showing up in the Spaces UI?"_ and _"how do I turn the whole Web Search tool off?"_.

The key principle to internalise:

> The env var puts the option in the UI; the API key in the env makes it actually work.

There are two independent gates:

1. **Visibility gate** — `ACTIVE_SEARCH_ENGINES` and `ACTIVE_INHOUSE_CRAWLERS` (plus API-key auto-activation) decide which entries appear in the **Search Engine** and **Web Page Reader** dropdowns in the Spaces UI.

2. **Functional gate** — for an engine or reader to actually run, its specific credentials (API key, Azure identity, GCP credentials, etc.) must also be configured. An engine can be visible but non-functional, in which case it appears in the dropdown but fails at runtime.

This page covers the visibility gate plus the platform-wide tool kill switch and the default-mode selector. For the functional gate (per-engine and per-reader credentials), see **Search Engine Setup** and **Web Page Reader Setup**.

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## Activation flow at startup

At runtime, the executor fetches credentials lazily and any engine or reader with missing credentials raises a configuration error before its first call.

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## Search Engine Activation

`ACTIVE_SEARCH_ENGINES` is a comma-separated list of engine identifiers. Each identifier appears in the engine selector if and only if it is on this list.

| Identifier    | Display name in the UI        | Required env to make it functional                                              | Setup page            |
|---------------|-------------------------------|------------------------------------------------------------------------------|-----------------------|
| `google`      | **Google Search**             | `GOOGLE_SEARCH_API_KEY`, `GOOGLE_SEARCH_API_ENDPOINT`, `GOOGLE_SEARCH_ENGINE_ID` | Search Engine Setup    |
| `bing`        | **Grounding with Bing**       | Azure identity (`AZURE_AI_PROJECT_ENDPOINT`, optional `AZURE_AI_ASSISTANT_ID`, `AZURE_AI_BING_RESOURCE_CONNECTION_STRING`, `AZURE_AI_BING_AGENT_MODEL`) | Search Engine Setup    |
| `vertexai`    | **Grounding with VertexAI**   | GCP credentials (Workload Identity in production; `VERTEXAI_SERVICE_ACCOUNT_CREDENTIALS` for development) | Search Engine Setup    |
| `brave`       | **Brave Search**              | `BRAVE_SEARCH_API_KEY`, `BRAVE_SEARCH_API_ENDPOINT`                          | Search Engine Setup    |
| `jina`        | **Jina Search**               | `JINA_API_KEY` (`JINA_SEARCH_API_ENDPOINT` defaults if unset)                 | Search Engine Setup    |
| `tavily`      | **Tavily Search**             | `TAVILY_API_KEY`                                                            | Search Engine Setup    |
| `firecrawl`   | **Firecrawl Search**          | `FIRECRAWL_API_KEY`                                                       | Search Engine Setup    |
| `custom_api`  | **Customized API Search**     | `CUSTOM_WEB_SEARCH_API_ENDPOINT` and friends (or in-Space configuration)   | Search Engine Setup    |

**Default:**`["google"]`.

Each Space can pick any one of the visible engines via its **Search Engine** setting.

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## Web Page Reader Activation

Reader activation has two layers:

1. **Built-in readers** — `ACTIVE_INHOUSE_CRAWLERS` is the explicit list. Defaults to `[\