# `ADK.Tool.FunctionTool`
[🔗](https://github.com/zeroasterisk/adk-elixir/blob/main/lib/adk/tool/function_tool.ex#L1)

Wraps any function as a tool with declaration metadata.

The `func` field accepts:

- An anonymous function (arity 1 or 2) — for runtime use
- An MFA tuple `{Module, :function, extra_args}` — compile-time safe
- A plain MF tuple `{Module, :function}` — shorthand for `{Module, :function, []}`

MFA tuples are called as `Module.function(ctx, args, ...extra_args)` (arity 2+)
or `Module.function(args, ...extra_args)` if the function has no context parameter.

## Examples

    # Anonymous function (runtime only)
    tool = ADK.Tool.FunctionTool.new(:greet,
      description: "Greet someone",
      func: fn _ctx, %{"name" => name} -> {:ok, "Hello, #{name}!"} end,
      parameters: %{
        type: "object",
        properties: %{name: %{type: "string"}},
        required: ["name"]
      }
    )

    # MFA tuple (compile-time safe, works in Plug init/1)
    tool = ADK.Tool.FunctionTool.new(:greet,
      description: "Greet someone",
      func: {MyApp.Tools, :greet},
      parameters: %{
        type: "object",
        properties: %{name: %{type: "string"}},
        required: ["name"]
      }
    )

# `mfa_tuple`

```elixir
@type mfa_tuple() :: {module(), atom(), list()} | {module(), atom()}
```

# `t`

```elixir
@type t() :: %ADK.Tool.FunctionTool{
  description: String.t(),
  func: function() | mfa_tuple(),
  name: String.t(),
  parameters: map()
}
```

# `new`

```elixir
@spec new(
  atom() | String.t(),
  keyword()
) :: t()
```

Create a new function tool.

# `run`

```elixir
@spec run(t(), ADK.ToolContext.t(), map()) :: ADK.Tool.result()
```

Execute the function tool.

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*Consult [api-reference.md](api-reference.md) for complete listing*