McpServer.Tool.Content (HTTP MCP Server v0.7.0)

Structs and helper functions for representing tool result content items.

This module provides typed structs and convenience functions for different types of content that can be returned from tool functions, following the MCP protocol specification.

Content Types

Text - Text content
Image - Image content with base64-encoded data
Resource - Embedded resource content

Usage

You can alias this module and use the helper functions to build tool results:

alias McpServer.Tool.Content, as: ToolContent

def search_tool(_conn, %{"query" => query}) do
  [
    ToolContent.text("Found 5 results for: #{query}"),
    ToolContent.text("Result 1: ..."),
    ToolContent.text("Result 2: ...")
  ]
end

def generate_chart(_conn, %{"data" => data}) do
  chart_image = create_chart(data)
  [
    ToolContent.text("Chart generated successfully"),
    ToolContent.image(chart_image, "image/png")
  ]
end

def read_file(_conn, %{"path" => path}) do
  [ToolContent.resource("file://#{path}", text: File.read!(path), mimeType: "text/plain")]
end

Low-level Struct API

iex> alias McpServer.Tool.Content
iex> text = Content.Text.new(text: "Hello, World!")
iex> text.text
"Hello, World!"

iex> image_data = <<137, 80, 78, 71, 13, 10, 26, 10>>
iex> image = Content.Image.new(data: image_data, mime_type: "image/png")
iex> image.mime_type
"image/png"

iex> resource = Content.Resource.new(uri: "file:///path/to/file.txt")
iex> resource.uri
"file:///path/to/file.txt"

Summary

Functions

image(data, mime_type)

Creates an image content item for tool responses.

resource(uri, opts \\ [])

Creates an embedded resource content item for tool responses.

text(text)

Creates a text content item for tool responses.

Functions

image(data, mime_type)

@spec image(binary(), String.t()) :: McpServer.Tool.Content.Image.t()

Creates an image content item for tool responses.

Returns a McpServer.Tool.Content.Image struct. The image data will be automatically base64-encoded during JSON serialization.

Parameters

data (binary): the raw image data
mime_type (string): the MIME type of the image (e.g., "image/png", "image/jpeg")

Examples

iex> image_data = <<137, 80, 78, 71, 13, 10, 26, 10>>
iex> McpServer.Tool.Content.image(image_data, "image/png")
%McpServer.Tool.Content.Image{data: <<137, 80, 78, 71, 13, 10, 26, 10>>, mime_type: "image/png"}

resource(uri, opts \\ [])

@spec resource(
  String.t(),
  keyword()
) :: McpServer.Tool.Content.Resource.t()

Creates an embedded resource content item for tool responses.

Returns a McpServer.Tool.Content.Resource struct.

Parameters

uri (string): the URI of the resource
opts (keyword list): optional keys include:
- :mimeType - MIME type of the resource
- :text - textual content of the resource
- :blob - binary content; base64-encoded during JSON serialization

Examples

iex> McpServer.Tool.Content.resource("file:///path/to/file.txt")
%McpServer.Tool.Content.Resource{uri: "file:///path/to/file.txt", text: nil, blob: nil, mime_type: nil}

iex> McpServer.Tool.Content.resource("file:///data.json", mimeType: "application/json", text: ~s({"key": "value"}))
%McpServer.Tool.Content.Resource{
  uri: "file:///data.json",
  mime_type: "application/json",
  text: ~s({"key": "value"}),
  blob: nil
}

iex> McpServer.Tool.Content.resource("file:///image.png", mimeType: "image/png", blob: <<255, 216, 255>>)
%McpServer.Tool.Content.Resource{
  uri: "file:///image.png",
  mime_type: "image/png",
  text: nil,
  blob: <<255, 216, 255>>
}

text(text)

@spec text(String.t()) :: McpServer.Tool.Content.Text.t()

Creates a text content item for tool responses.

Returns a McpServer.Tool.Content.Text struct.

Parameters

text (string): the text content to return

Examples

iex> McpServer.Tool.Content.text("Hello, World!")
%McpServer.Tool.Content.Text{text: "Hello, World!"}

iex> McpServer.Tool.Content.text("Operation completed successfully")
%McpServer.Tool.Content.Text{text: "Operation completed successfully"}