docs(tools): add Quick Selection Guide and common scenarios

Adds decision tree and real-world examples to the existing Tools page:
- ASCII decision tree for quick tool type selection
- 6 common scenarios with conservative UI path guidance
- Softer tone, consistent with existing docs
- Integrated with existing taxonomy section

Addresses user confusion while avoiding duplication.
AI-assisted drafting; manually reviewed and validated.

Signed-off-by: Hera and Hades

Author: HeraAndHades

docs/features/extensibility/plugin/tools/index.mdx

@@ -47,7 +47,65 @@ These are **Python scripts** that run directly within the Open WebUI environment
 - **MCPO (Proxy)**: Most community MCP servers use `stdio` (local command line). To use these in Open WebUI, you use the [**MCPO Proxy**](../../plugin/tools/openapi-servers/mcp.mdx) to bridge the connection.
 
 ### 4. OpenAPI / Function Calling Servers
-Generic web servers that provide an OpenAPI (`.json` or `.yaml`) specification. Open WebUI can ingest these specs and treat every endpoint as a tool.
+Generic web servers that provide an OpenAPI (`.json` or `.yaml`) specification.
+Open WebUI can ingest these specs and treat every endpoint as a tool.
+
+---
+
+## Quick Selection Guide
+
+🎯 Not sure which extension type to use?
+Start here.
+
+### Decision Tree
+
+```text
+Do you need a built-in capability (e.g., Web Search or other native features)?
+├─ Yes → Use Native Features (built-in)
+│   → Enable via Admin Panel settings (feature-dependent),
+│     then toggle in-chat if available
+└─ No → Do you need to run custom Python on the Open WebUI server?
+    ├─ Yes →
+    │   ├─ Is it a simple input/output transformation on messages?
+    │   │   ├─ Yes → Use Functions (Filters / Pipes)
+    │   │   └─ No → Use Workspace Tools
+    │   └─ Do you need to offload heavy/long-running work?
+    │       ├─ Yes → Use Pipelines (separate service/container)
+    │       └─ No → Use Workspace Tools
+    └─ No → Do you need to connect to external services via an API/spec?
+        ├─ Yes →
+        │   ├─ Standard REST API with an OpenAPI spec → Use OpenAPI Servers
+        │   └─ MCP-compatible service → Use MCP (native HTTP or via MCPO proxy)
+        └─ No → You may not need tools—start with prompts and built-in features.
+```
+
+### Common Scenarios
+
+**"I want the model to search the web."**
+→ Use Native Web Search (no code).
+Enable it in the Admin Panel (Web Search settings),
+then toggle it in the chat UI if applicable.
+
+**"I need a custom weather lookup (or other API call)."**
+→ Use Workspace Tools.
+Write Python to call the API and return structured results.
+
+**"I want to transform messages (e.g., redact sensitive text) before sending to the model."**
+→ Use Functions (Filter).
+Keep the logic lightweight,
+and review any compliance/security requirements for your use case.
+
+**"I need to run heavy ML workloads (classification, extraction, etc.) without slowing down the app."**
+→ Use Pipelines.
+Run the workload in a separate service/container.
+
+**"I want to connect to my company's internal REST API."**
+→ Use an OpenAPI Server.
+Provide an OpenAPI spec so tools can be generated automatically.
+
+**"I have an MCP server (e.g., from a desktop workflow) and want to use it in Open WebUI."**
+→ Use MCP via MCPO to bridge stdio-based MCP servers to HTTP,
+then connect it under Settings → Connections.
 
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