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Type Definitions

Response Types​

MCPResponse​

JSON-RPC response returned by an MCP tool invocation.

interface MCPResponse {
  jsonrpc: '2.0';
  id: string | number | null;
  result?: MCPResult;
  error?: MCPError;
}

MCPResult​

Successful MCP tool response payload.

interface MCPResult {
  content?: MCPContentMessage[];
  data?: unknown;
  [key: string]: unknown;
}

MCPError​

Shape of an MCP error, following the JSON-RPC structure used by MCP servers.

interface MCPError {
  code: number;
  message: string;
  data?: unknown;
}

MCPContentMessage​

Individual response message chunk returned by an MCP tool.

interface MCPContentMessage {
  role: string;
  type: string;
  content: unknown;
}

Server Types​

MCPCapabilities​

Defines the capabilities that an MCP server or client supports.

interface MCPCapabilities {
  tools?: {
    listChanged?: boolean;
  };
  resources?: {
    subscribe?: boolean;
    listChanged?: boolean;
  };
  prompts?: {
    listChanged?: boolean;
  };
  logging?: {
    level?: string;
  };
}

MCPInitializeParams​

Parameters sent during MCP initialization.

interface MCPInitializeParams {
  protocolVersion: string;
  capabilities: MCPCapabilities;
  clientInfo: {
    name: string;
    version: string;
  };
}

MCPInitializeResult​

Result returned from MCP initialization.

interface MCPInitializeResult {
  protocolVersion: string;
  capabilities: MCPCapabilities;
  serverInfo: {
    name: string;
    version: string;
  };
  instructions?: string;
}

MCPTool​

Represents a tool provided by an MCP server.

interface MCPTool {
  name: string;
  description?: string;
  inputSchema: {
    type: 'object';
    properties?: Record\<string, any\>;
    required?: string[];
  };
}

MCPResource​

Represents a resource provided by an MCP server.

interface MCPResource {
  uri: string;
  name: string;
  description?: string;
  mimeType?: string;
}

MCPToolsListResult​

Result from listing tools on an MCP server.

interface MCPToolsListResult {
  tools: MCPTool[];
}

MCPResourcesListResult​

Result from listing resources on an MCP server.

interface MCPResourcesListResult {
  resources: MCPResource[];
}

Configuration Types​

MCPStdinSubprocessOptions​

Configuration options for creating an MCP subprocess.

interface MCPStdinSubprocessOptions extends JsonRpcSubprocessOptions \{
  requestTimeout?: number;
  allowDebugLogging?: boolean;
}