Traditional REST APIs: General-Purpose, Fixed Contracts
~10 min read
APIs are general-purpose software-to-software interfaces with a fixed contract. When that contract changes — even adding one new parameter — every integrated client has to be manually updated.
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Key points
- •APIs are general-purpose software-to-software interfaces with a fixed contract, not designed with AI agents specifically in mind
- •When the contract changes (e.g. adding a required parameter), every integrated client must be manually updated
- •This is a structural property of the fixed-contract model, not a flaw specific to poorly-designed APIs
- •Well-managed for traditional integration via versioning and deprecation practices
- •Becomes a much bigger problem for AI agents needing to discover and adapt to changing capabilities without manual updates — exactly what MCP addresses