> For the complete documentation index, see [llms.txt](https://docs.toolregistry.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.toolregistry.ai/concepts/integrations/custom-integrations.md).

# Custom Integrations

**Bring anything with an API spec or MCP.**

* **OpenAPI**: upload a spec; the system generates callable tools.
* **Remote MCP**: register a remote MCP server and let agents call it.
* **Auth**: define OAuth/API key flows and store tokens securely in ToolRegistry.
* **Control**: endpoint‑level allow‑lists and approvals

**Best practices**

* Keep specs small and focused on the actions you actually want to allow.
* Keep in mind that MCP allow lists/block lists are probabilistic in nature and always best effort basis
* Version your specs; treat changes as deployments