# `ExMCP.Approval`
[🔗](https://github.com/azmaveth/ex_mcp/blob/v1.0.0/lib/ex_mcp/approval.ex#L1)

Behaviour for implementing approval handlers in MCP clients.

This behaviour defines the callback for handling approval requests
when a server wants to perform actions that require user consent.

# `approval_data`

```elixir
@type approval_data() :: map()
```

# `approval_opts`

```elixir
@type approval_opts() :: keyword()
```

# `approval_result`

```elixir
@type approval_result() ::
  {:approved, approval_data()} | {:denied, reason :: String.t()}
```

# `approval_type`

```elixir
@type approval_type() :: :sampling | :tool_call | :resource_access | atom()
```

# `request_approval`

```elixir
@callback request_approval(approval_type(), approval_data(), approval_opts()) ::
  approval_result()
```

Requests approval for an action.

## Parameters

- `type` - The type of approval being requested (e.g., :sampling, :tool_call)
- `data` - The data associated with the approval request
- `opts` - Additional options for the approval handler

## Returns

- `{:approved, data}` - The request was approved, possibly with modified data
- `{:denied, reason}` - The request was denied with a reason

## Examples

    def request_approval(:sampling, %{"messages" => messages}, opts) do
      # Show UI to user for approval
      case get_user_consent(messages) do
        :yes -> {:approved, %{"messages" => messages}}
        :no -> {:denied, "User declined the request"}
      end
    end

---

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