Improve Tool interface typing

[MQ37]

Use something like this so the tool type is more explicit:

interface Tool {
  type: string;
  name: string;
  ...
}

interface InternalTool extends Tool {
  type: 'internal';
}

interface ActorTool extends Tool {
  type: 'actor';
}

[jirispilka]

Also ToolBase should extend tool from modelcontextprotocol types.js

export interface ToolBase extends Tool {
    /** Unique name/identifier for the tool */
    name: string;
    /** Description of what the tool does */
    description: string;
    /** JSON schema defining the tool's input parameters */
    inputSchema: object;
    /** AJV validation function for the input schema */
    ajvValidate: ValidateFunction;
}