[agent builder] Add built-in agents reference page

explore-analyze/ai-features/agent-builder/built-in-agents.md

@@ -0,0 +1,69 @@
+---
+navigation_title: "Built-in agents reference"
+applies_to:
+  stack: preview =9.2, ga 9.3
+  serverless: preview
+products:
+  - id: kibana
+  - id: observability
+  - id: security
+  - id: cloud-serverless
+---
+
+# {{agent-builder}} built-in agents reference
+
+This page lists the built-in agents available in {{agent-builder}}. Built-in agents are pre-configured by Elastic with specific instructions and tools to handle common use cases. 
+
+Unlike custom agents, you cannot modify or delete these agents. However, they serve as excellent examples for [building your own custom agents](agent-builder-agents.md#create-a-new-agent-in-the-gui).
+
+## Availability and location
+
+The availability of specific agents depends on your active solution and whether you have enabled {{agent-builder}} in that space.
+
+## Elastic AI Agent
+```{applies_to}
+stack: preview =9.2, ga 9.3
+```
+
+The **Elastic AI Agent** is the default general-purpose agent for {{es}}. It is designed to help with a wide range of tasks, from writing {{esql}} queries to exploring your data indices.
+
+**Availability:**
+* **All views:** Available in {{es}}, {{observability}}, Security, and Classic views.
+
+**Assigned Tools:**
+* All **Platform core tools** (e.g., `list_indices`, `execute_esql`, `get_document_by_id`)
+* `product_documentation`
+
+## {{observability}} Agent
+```{applies_to}
+stack: preview =9.3
+```
+
+A specialized agent for logs, metrics, and traces. It is designed to assist with infrastructure monitoring and application performance troubleshooting.
+
+**Availability:**
+* **Observability** view
+* **Classic** view
+
+**Assigned Tools:**
+* All **{{observability}} tools** (e.g., `observability.get_alerts`, `observability.get_services`, `observability.get_log_change_points`)
+* All **Platform core tools**
+
+## Threat Hunting Agent
+```{applies_to}
+stack: preview =9.3
+```
+
+A specialized agent for security alert analysis tasks, including alert investigation and security documentation. It helps analysts triage alerts and understand complex security events.
+
+**Availability:**
+* **Security** view
+* **Classic** view
+
+**Assigned Tools:**
+* All **Security tools** (e.g., `security.alerts`, `security.entity_risk_score`, `security.attack_discovery_search`)
+* All **Platform core tools**
+
+## Related pages
+
+- [Create a new agent](agent-builder-agents.md#create-a-new-agent-in-the-gui)

explore-analyze/toc.yml

@@ -178,6 +178,8 @@ toc:
             children:
               - hidden: ai-features/agent-builder/standalone-and-flyout-modes.md
           - file: ai-features/agent-builder/agent-builder-agents.md
+            children:
+            - file: ai-features/agent-builder/built-in-agents.md
           - file: ai-features/agent-builder/tools.md
             children:
               - file: ai-features/agent-builder/tools/esql-tools.md