Integrate Mcp Server

Workflow

1. Discover MCP server and tools

• Identify the MCP server: name, run command, and args (e.g. python, ["-m", "mcp_server_fetch"]).
• If present, read mcps/<server>/tools/*.json or src/Plugins/DOCS/MCPIntegrations/<name>-plugin-integration.md for tool names and parameters.
• Check McpCommandValidator and project conventions (e.g. allowed commands like python, python3, dotnet) so the plugin uses a valid command.

2. Create the nested plugin

• Add src/Plugins/NestedKernel/SK/Nested[Name]Plugin.cs following NestedFetchPlugin or NestedFilesystemPlugin.
• Use the NestedMCPKernelPlugin example (in src/Plugins/Examples/NestedKernels/) as implementation reference; the generic NestedMCPKernelPlugin is not registered in StandardKernel: lazy async kernel (Lazy<Task<Kernel>>), MCP client lifecycle, disposal, retry for transient failures, thread-safe initialization. New MCP integrations use Nested[Name]Plugin (e.g. NestedFetchPlugin) and register in AddNestedKernelPlugins.
• Expose one main function (e.g. Ask[Name]Agent) that takes user message and optional ChatHistory; pass ChatHistory via kernel arguments if the project uses context injection.
• Ensure the plugin implements IDisposable and IAsyncDisposable and disposes the MCP client.

Reference files:

• src/Plugins/NestedKernel/SK/NestedFetchPlugin.cs
• src/Plugins/NestedKernel/SK/NestedFilesystemPlugin.cs
• src/Plugins/Examples/NestedKernels/NestedMCPKernelPlugin.cs (example MCP pattern)

3. Add system message in KernelConstants

• In src/Utilities/KernelConstants.cs, add a new public const string (e.g. [Name]SubKernelSystemMessage).
• Content: role + which tools to use + "Always base your entire response on the tool results" + "never invent/fabricate" wording.
• Follow the style of FetchSubKernelSystemMessage and FilesystemSubKernelSystemMessage.

4. Register plugin in StandardKernel

• In src/AnimalKernel/Core/StandardKernel.cs, inside AddNestedKernelPlugins:
  • Instantiate the new plugin (e.g. new NestedFetchPlugin(_loggerFactory, _endpoint, _modelId)), passing any required ctor args.
  • Call builder.Plugins.AddFromObject(pluginInstance, "[Name]Agent").
  • Add to _pluginInstances["[Name]Agent"] = pluginInstance.
  • If the plugin is disposable, add it to _disposablePlugins for cleanup (follow existing nested plugins in that method).

5. Add integration tests

• In src/IntegrationTesterApp/TestCaseDefinitions.cs, add test cases that:
  • Use a prompt that should be handled by the new agent.
  • Set expected tools to include the new agent’s main function (e.g. FetchAgent.AskFetchAgent).
  • Set forbidden tools to other agents where appropriate.
  • Set required response keywords consistent with the system message and tool behavior.
  • Assign tags (e.g. fetch, filesystem) for filtered runs.

Use the add-plugin-test skill for structure and fields. After adding tests, run the smart-test-runner skill (or .\run-tests.ps1 -t <tag>) and fix code before relaxing assertions.

Reference implementations and docs

Checklist before delivering

• MCP server command/args and tool descriptors (or docs) identified.
• Nested[Name]Plugin.cs created following NestedFetchPlugin/NestedFilesystemPlugin and NestedMCPKernelPlugin pattern; implements IDisposable/IAsyncDisposable.
• New system message constant added in KernelConstants.cs and used by the nested plugin’s internal kernel.
• Plugin registered in AddNestedKernelPlugins: AddFromObject, _pluginInstances, and _disposablePlugins if applicable.
• At least one integration test added in TestCaseDefinitions.cs with expected tool, keywords, and tags.
• Tests run (e.g. via smart-test-runner or .\run-tests.ps1 -t <tag>); failures addressed by fixing code, not by weakening assertions.