Integrate MCP Server

Guides the agent through adding a new MCP (Model Context Protocol) server integration to AnimalAL-v1. The workflow creates a nested kernel plugin that wraps the MCP server, wires a system message, registers the plugin in StandardKernel, and adds integration tests. Follows the patterns in DOCS/MCPIntegrations and reference implementations (NestedFetchPlugin, NestedFilesystemPlugin).

When to Apply

• •User says: "add MCP server", "integrate MCP server", "wire MCP tools", "add MCP integration for [server]"
• •User wants to expose a new MCP server's tools to the kernel via a nested plugin
• •User asks how to add or connect a new MCP server to the project
• •User refers to an MCP server by name (e.g. fetch, filesystem) and wants it integrated

Discovery / Gather

Before generating or editing files, gather:

1. •

   MCP server identity

   • •Server name (e.g. fetch, filesystem) and how it is run (command and args, e.g. python -m mcp_server_fetch).
   • •If the project has tool descriptors under mcps/<server>/tools/*.json, read them to know tool names and parameters.
2. •

   Plugin name and agent name

   • •Use PascalCase; plugin will be Nested[Name]Plugin and agent name in StandardKernel will be "[Name]Agent" (e.g. FetchAgent, FilesystemAgent).
3. •

   System message

   • •One- or two-sentence instruction for the sub-kernel: what it does, which tools to use, and that it must not fabricate data. See existing constants in KernelConstants.cs (e.g. FetchSubKernelSystemMessage, FilesystemSubKernelSystemMessage).
4. •

   Tests

   • •At least one prompt that should trigger the new agent, expected tool(s), and required response keywords. Use add-plugin-test patterns if creating multiple test cases.

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.