Anubis.Server.Component.Resource behaviour (anubis_mcp v0.14.0)
Defines the behaviour for MCP resources.
Resources represent data that can be read by the client, such as files, documents, or any other content. Each resource is identified by a URI and can provide content in various formats.
Example
defmodule MyServer.Resources.Documentation do
@behaviour Anubis.Server.Behaviour.Resource
alias Anubis.Server.Frame
@impl true
def uri, do: "file:///docs/readme.md"
@impl true
def name, do: "Project README"
@impl true
def description, do: "The main documentation for this project"
@impl true
def mime_type, do: "text/markdown"
@impl true
def read(_params, frame) do
case File.read("README.md") do
{:ok, content} ->
# Can track access in frame
new_frame = Frame.assign(frame, :last_resource_access, DateTime.utc_now())
{:ok, content, new_frame}
{:error, reason} ->
{:error, "Failed to read README: #{inspect(reason)}"}
end
end
end
Example with dynamic content
defmodule MyServer.Resources.SystemStatus do
@behaviour Anubis.Server.Behaviour.Resource
@impl true
def uri, do: "system://status"
@impl true
def name, do: "System Status"
@impl true
def description, do: "Current system status and metrics"
@impl true
def mime_type, do: "application/json"
@impl true
def read(_params, frame) do
status = %{
uptime: System.uptime(),
memory: :erlang.memory(),
user_id: frame.assigns[:user_id],
timestamp: DateTime.utc_now()
}
{:ok, Jason.encode!(status), frame}
end
end
Summary
Callbacks
Returns the MIME type of the resource content.
Returns the name
that identifies this resource.
Reads the resource content.
Returns the title that identifies this resource.
Returns the URI that identifies this resource.
Types
Callbacks
@callback mime_type() :: String.t()
Returns the MIME type of the resource content.
Common MIME types:
text/plain
for plain texttext/markdown
for Markdownapplication/json
for JSON datatext/html
for HTMLapplication/octet-stream
for binary data
@callback name() :: String.t()
Returns the name
that identifies this resource.
Intended for programmatic or logical use, but used as a display name in past specs or fallback (if title isn't present).
@callback read(params :: params(), frame :: Anubis.Server.Frame.t()) :: {:reply, response :: Anubis.Server.Response.t(), new_state :: Anubis.Server.Frame.t()} | {:noreply, new_state :: Anubis.Server.Frame.t()} | {:error, error :: Anubis.MCP.Error.t(), new_state :: Anubis.Server.Frame.t()}
Reads the resource content.
Parameters
params
- Optional parameters from the client (typically empty for resources)frame
- The server frame containing context and state
Return Values
{:ok, content}
- Resource read successfully, frame unchanged{:ok, content, new_frame}
- Resource read successfully with frame updates{:error, reason}
- Failed to read resource
Content Types
The content should match the declared MIME type:
- For text types, return a String
- For binary types, return binary data
- For JSON, return the JSON-encoded string
@callback title() :: String.t()
Returns the title that identifies this resource.
Intended for UI and end-user contexts — optimized to be human-readable and easily understood, even by those unfamiliar with domain-specific terminology.
If not provided, the name should be used for display.
@callback uri() :: String.t()
Returns the URI that identifies this resource.
The URI should be unique within the server and follow standard URI conventions. Common schemes include:
file://
for file-based resourceshttp://
orhttps://
for web resources- Custom schemes for application-specific resources