List all MCP tools the Expert Builder can attach to an expert.

Source of truth: the tool manifests in the backend tool registry. Each manifest's static [[tools]] is enumerated; OpenAPI-handler manifests fall back to canonical entries in TOOL_TO_KEY_MAP (the dispatcher's allow-list). Dynamic-MCP providers with no static tools emit a single provider-level bundle so users can attach the whole server. The parcha-tools document-verification tools are appended statically — they are native MCP tools served by the parcha-tools sibling service, not registry providers.