MCP tools should be expandable via tool-plugins

[cdcabrera]

Description

MCP tools can be converted towards using a plugin architecture.

Acceptance criteria

• MCP tools are expandable via cli or programmatically
• Tools should receive some level of context for settings and functionality
• Consuming tools will include the phases
  • local files
  • npm packages - review of existing work still required

[cdcabrera]

Status update.

Tools-as-plugins work currently encompasses 2 parts

Part 1 includes - target consumer development - targeted for release late Dec 2025

• Inline tools for embedded MCP servers - Node.js >= 20 (Possibly also works with Node.js 18 but we're not actively checking)
• Local files and NPM/Packages - Node.js >= 22

Part 2 includes - target consumer everyone

• Remote files and possibly NPM/Packages - Node.js >= 22
• YML and remote YML - Node.js >= 22

What's needed?

The requirements for inline, or embedding, and running your own flavor of PF MCP boils down to returning the right format, 4 basic things

• name - a concise descriptive MCP tool name
• description - a descriptive prompt to guide the model regarding what your tool is, potentially how to use it.
• inputSchema - basically a JSON schema object describing, for the model, the type and general structure of data the tool accepts.
• handler - the tool implementation, a callback, meant to manipulate data based on the provide parameters (inputSchema) then returned it back to the model

Syntax

The format for developers is available in a few formats

Inline functions

Inline functions, Node.js >= 20support, will be similar to...

import { start, createMcpTool, type PfMcpInstance, type ToolCreator } from '@patternfly/patternfly-mcp';

// A convenience wrapper for helping write PF-MCP tooling, not required.
const echoTool: ToolCreator = createMcpTool({
  name: 'echoAMessage',
  description: 'Echo back the provided user message.',
  inputSchema: {
    type: 'object',
    properties: { message: { type: 'string' } },
    required: ['message']
  },
  handler: (args: { message: string }) => ({ text: `You said: ${args.message}` })
});

// Basic assigned func returning the required tuple response
const loremIpsumTool = () => [
  'lorem-ipsum-name'
  {
    description: 'The lorem ipsum tool desc'
    inputSchema: { ... }
  },
  () => ({ ... })
];

const dolorSitTool = [
  'dolor-sit-name'
  {
    description: 'The dolor sit tool desc'
    inputSchema: { ... }
  },
  async () => ({ ... })
];

const server: PfMcpInstance = await start({
  toolModules: [echoTool, loremIpsumTool, dolorSitTool]
});

setTimeout(async () => server.stop(), 10000);

Local files

Only JS files with ESM exports are support, limited to Node.js >= 22

// server.js
import { start, type PfMcpInstance } from '@patternfly/patternfly-mcp';

const server: PfMcpInstance = await start({
  toolModules: ['./my-local-file/relative-to-the-server.js', '/users/myusername/absolute/path/tool.js']
});

setTimeout(async () => server.stop(), 10000);

// tool.js
export default const echo_plugin_tool = options => [
  'echo_plugin_tool',
  {
    description: 'Echo back the provided args, but with a different description',
    inputSchema: { additionalProperties: true }
  },
  args => ({
    args,
    options,
    content: [
      {
        type: 'text',
        text: JSON.stringify(args)
      }
    ]
  })
];