What an API is ## What an API is An API (Application Programming Interface) is how one computer program talks to another. Alex Rattray's analogy captures the role APIs play: APIs are the dendrites of the internet — the connection points where programs, like neurons, exchange information. Without those connections, there is no thought — and no internet. APIs are the dendrites of the internet. Why APIs matter for agents ## Why APIs matter for agents In the channel's material, APIs are the layer agents must reach to be useful: an agent that takes action on your behalf — using tools, changing systems, consulting information sources — depends on existing websites and APIs being plumbed through so agents can talk to them. The material explores two ways agents interface with APIs: - MCP servers that expose API endpoints as tools — where naive one-to-one translation of a big API (like Stripe's, with hundreds of endpoints) burns huge amounts of context before real work starts. - Code execution against the API's typed SDK, with static typing acting as the guard against hallucinated method calls. Notably, the material argues that security cannot be handled at the MCP layer, because anything in the underlying API remains reachable under the hood — security has to live at the API layer itself, through OAuth with granular permissions and proper scopes. - An API is how one program talks to another — the connection points of the internet. - Agents act through APIs, whether via MCP tools or by writing code against typed SDKs. - Security for agent access belongs at the API layer, not the MCP layer.