dart_mcp (Package of the Week)

Added: 2026-05-06

[00:00:07]The Dart MCP package provides a framework for building model context protocol servers and clients, otherwise known as MCP.

[00:00:16]It's a standard for connecting AI models to resources, tools, and [music] customize workflows.

[00:00:22]For example, it powers the Dart and Flutter MCP server.

[00:00:26]Resources [music] provide access to local files, structured data, and any additional context that augments the model.

[00:00:33]>> [music] >> Tools enable models to execute some action or retrieve some information.

[00:00:38]And prompts guide users to follow a predefined path with each interaction.

[00:00:44]MCP servers act as universal adapters for exposing these resources, tools, and prompts. And MCP clients act as universal adapters for consuming these resources, tools, and prompts.

[00:00:56]Let's build an MCP server with a tool that helps me to convert between imperial and metric units. Each of the server features are provided as Dart mixins.

[00:01:06]Define a new tool by providing a name, description, and input schema.

[00:01:11]Next, declare a function that accepts [music] a call tool request and returns a future or call tool result. Call tool request has an arguments property, which contains the data needed to fulfill the request.

[00:01:26]It matches the properties list in the input schema.

[00:01:29]After the calculations are done, the function should return a call tool result with a list of content objects [music] containing the result.

[00:01:39]Content objects can be text, images, audio, or an embedded resource.

[00:01:44]Finally, remember to register the tool to link the tool definition to the tool implementation.

[00:01:51]Let's start the MCP server on a separate process using dart run.

[00:01:56]Next, using the MCP client constructor, create an MCP client and connect it to the MCP server.

[00:02:04]In this example, [music] let's assume the server and client are running on the same machine. So, we're using the console's input output channel.

[00:02:12]However, if the MCP server and client were on separate machines, they could still communicate using a stream channel.

[00:02:20]A long-lived two-way communications pipe between a server and client.

[00:02:25]Before we can query it, initialize a handshake with the MCP server to declare what protocol to use and to discover what tools, resources, and prompt features are provided by the server.

[00:02:36]To initiate a tool request, construct a call tool request and provide the tool name and a map of arguments.

[00:02:44]Then use the server's call tool method and provide your call tool request.

[00:02:49]For more information on Dart MCP and all the other packages, [music] head to pub.dev.

[00:03:01]>> [music]