> For the complete documentation index, see [llms.txt](https://help.clickatell.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.clickatell.com/developers-api-reference/developers-archive/sms-rest-api-overview.md). # SMS Rest API overview {% hint style="warning" %} This section contains technical documentation for the **Developer Central** and **Secure** products, relevant to all Clickatell accounts created **before 15 November 2016.** It also contains some **Platform** developer documentation referring to APIs that have since been updated or are no longer supported. Refer to the rest of this Dev Docs site for the latest API documentation. {% endhint %} --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://help.clickatell.com/developers-api-reference/developers-archive/sms-rest-api-overview.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.