I don't think any of the mainstream vendor APIs require MCP for tool use - they all supported functions (generally defined using a chunk of OpenAPI JSON schema) before the MCP spec gained widespread acceptance and continue to do so today.
Yep, the Anthropic API supported tool use well before an MCP-related construct was added to the API (MCP connector in May of this year).
While it's not an API, Anthropic's Agent SDK does require MCP to use custom tools.
Yep, the Anthropic API supported tool use well before an MCP-related construct was added to the API (MCP connector in May of this year).
While it's not an API, Anthropic's Agent SDK does require MCP to use custom tools.