feat(gateway): MCP client — connect to external MCP servers as agent tools (#127) (#141)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

apps/gateway/src/mcp-client/mcp-client.dto.ts

@@ -0,0 +1,33 @@
+/**
+ * DTOs for MCP client configuration and tool discovery.
+ */
+
+export interface McpServerConfigDto {
+  /** Unique name identifying this MCP server */
+  name: string;
+  /** URL of the MCP server (streamable HTTP or SSE endpoint) */
+  url: string;
+  /** Optional HTTP headers to send with requests (e.g., Authorization) */
+  headers?: Record<string, string>;
+}
+
+export interface McpToolDto {
+  /** Namespaced tool name: "<serverName>__<toolName>" */
+  name: string;
+  /** Human-readable description of the tool */
+  description: string;
+  /** JSON Schema for tool input parameters */
+  inputSchema: Record<string, unknown>;
+  /** MCP server this tool belongs to */
+  serverName: string;
+  /** Original tool name on the remote server */
+  remoteName: string;
+}
+
+export interface McpServerStatusDto {
+  name: string;
+  url: string;
+  connected: boolean;
+  toolCount: number;
+  error?: string;
+}