Mention that tools become toolset internally (#2395)

Co-authored-by: Douwe Maan <[email protected]>

Author: HamzaFarhan

docs/tools.md

@@ -12,7 +12,7 @@ There are a number of ways to register tools with an agent:
 - via the [`@agent.tool_plain`][pydantic_ai.Agent.tool_plain] decorator — for tools that do not need access to the agent [context][pydantic_ai.tools.RunContext]
 - via the [`tools`][pydantic_ai.Agent.__init__] keyword argument to `Agent` which can take either plain functions, or instances of [`Tool`][pydantic_ai.tools.Tool]
 
-For more advanced use cases, the [toolsets](toolsets.md) feature lets you manage collections of tools (built by you or provided by an [MCP server](mcp/client.md) or other [third party](#third-party-tools)) and register them with an agent in one go via the [`toolsets`][pydantic_ai.Agent.__init__] keyword argument to `Agent`.
+For more advanced use cases, the [toolsets](toolsets.md) feature lets you manage collections of tools (built by you or provided by an [MCP server](mcp/client.md) or other [third party](#third-party-tools)) and register them with an agent in one go via the [`toolsets`][pydantic_ai.Agent.__init__] keyword argument to `Agent`. Internally, all `tools` and `toolsets` are gathered into a single [combined toolset](toolsets.md#combining-toolsets) that's made available to the model.
 
 !!! info "Function tools vs. RAG"
     Function tools are basically the "R" of RAG (Retrieval-Augmented Generation) — they augment what the model can do by letting it request extra information.