Plugin-Based Request Handler Assemblies

In small applications, request handlers may live directly inside the main server project. In larger systems, a plugin-based architecture is often more scalable. Groups of related request handlers can be implemented in separate assemblies that are built independently and copied into a known plugin folder at deployment time.

The "Automatic Discovery and Registration" page described the process of scanning assemblies and loading only those decorated with the RpcAssembly attribute. In practice, such assemblies are usually deployed into a predefined plugin folder configured in the application's appsettings.json file, similar to:

{
  "McpTools": {
    "PluginFolder": "Modules"
  }
}

At startup, the host scans this folder, loads matching assemblies, discovers request handlers, and registers them automatically.

Projects that produce plugin assemblies can use an MSBuild Target to automatically copy their output into the configured Modules folder after the build completes. For example:

<Target Name="CopyOutputToMcpModules" AfterTargets="Build">
  <MakeDir Directories="Modules" />
  <ItemGroup>
    <McpPluginFiles Include="$(TargetDir)*.dll" />
    <McpPluginFiles Include="$(TargetDir)*.pdb" />
    <McpPluginFiles Include="$(TargetDir)*.json" />
  </ItemGroup>
  <Copy SourceFiles="@(McpPluginFiles)" DestinationFolder="Modules" SkipUnchangedFiles="true" />
</Target>

The exact destination path depends on the solution structure and deployment model. The example above uses a simplified folder layout for clarity.

Result

The host does not need to know about every module at compile time. New handler assemblies can be added by deployment, discovered at startup, and exposed through /rpc/tools and MCP tools/list.

 

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