# `ConduitMcp.Component.Schema`
[🔗](https://github.com/nyo16/conduit_mcp/blob/v0.10.1/lib/conduit_mcp/component/schema.ex#L1)

Schema DSL for defining parameters in Component modules.

Provides a simple `schema do ... end` block with `field` declarations
that generate both JSON Schema (for MCP client introspection) and
NimbleOptions schemas (for server-side runtime validation).

## Example

    defmodule MyApp.Echo do
      use ConduitMcp.Component, type: :tool, description: "Echoes text"

      schema do
        field :text, :string, "The text to echo", required: true, max_length: 150
        field :count, :integer, "Repeat count", default: 1, min: 1, max: 10
      end

      @impl true
      def execute(%{text: text, count: count}, _conn) do
        text(String.duplicate(text, count))
      end
    end

## Supported Types

- `:string` — String values
- `:integer` — Integer values
- `:number` — Numeric values (float)
- `:boolean` — Boolean values
- `:object` — Nested objects (block form with nested `field` calls; the
  blockless form declares an open object with no constrained keys)
- `:array` / `{:array, item_type}` — Arrays. Use the block form with
  `items/1,2` to constrain the item type

## Field Options

- `required: true` — Mark as required (default: false)
- `default: value` — Default value
- `enum: [...]` — Allowed values
- `min: n` / `max: n` — Numeric constraints
- `min_length: n` / `max_length: n` — String length constraints
- `validator: fn` — Custom validator function
- `additional_properties: bool` — For `:object`: whether keys the block did
  not declare are accepted. Defaults to `false` when the field declares
  nested fields and `true` when it does not, and drives
  `"additionalProperties"` in the generated JSON Schema so the published
  schema matches what is enforced.

## Nested Objects and Array Items

Nested fields are enforced at runtime to any depth — required, types, and
every option above — and undeclared keys are rejected. Array item schemas are
published for clients but not enforced server-side; see
`ConduitMcp.Validation.SchemaConverter` for why.

Handlers receive string keys at every depth below the top level.

# `field`
*macro* 

Defines a field in the component schema.

## Examples

    # Simple field
    field :name, :string, "User's name", required: true

    # Field with options
    field :age, :integer, "User's age", min: 0, max: 150

    # Field without description (uses opts keyword)
    field :tags, {:array, :string}, "Tag list"

    # Nested object field
    field :address, :object, "Mailing address", required: true do
      field :street, :string, "Street", required: true
      field :city, :string, "City", required: true
    end

    # Open object field — any keys accepted
    field :metadata, :object, "Arbitrary metadata"

    # Array of objects
    field :rows, :array, "Rows" do
      items :object do
        field :id, :integer, "Row id", required: true
      end
    end

# `items`
*macro* 

Declares the item type of the enclosing `:array` field.

Item schemas are published to clients in the JSON Schema but are **not**
enforced server-side — NimbleOptions cannot attach a nested schema to a list
element type. Validate item contents in your `execute/2`.

## Examples

    field :tags, :array, "Tags" do
      items :string
    end

    field :users, :array, "Users" do
      items :object do
        field :name, :string, "Name", required: true
      end
    end

# `items`
*macro* 

# `schema`
*macro* 

Defines the parameter schema for a component.

Wraps `field` declarations and accumulates them into `@component_fields`.

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