Matchup
Hand-written SDK vs MCP server
These two serve different callers: an SDK serves a developer writing code, an MCP server serves an agent choosing tools. Running them head to head shows where each is strong, and that auth (counted double here) is hard for both.
Verdict
Too close to call: Hand-written SDK 10, MCP server over your API 9.
Hand-written SDK 10/18 MCP server over your API 9/18
Hand-written SDK takes auth handling and error handling. MCP server over your API takes maintenance and mCP readiness. Even on typing.
| Criterion | Hand-written SDK | MCP server over your API |
|---|---|---|
| TypingEven | Solid Types can be as idiomatic as the authors make them, but they are written by hand and can drift from the API as it changes. | Solid Each tool declares its inputs as JSON Schema, which the agent reads. How tight those schemas are depends on how the server was built. Check: Model Context Protocol specification |
| Auth handling×2Edge: Hand-written SDK | Strong Full control: any flow, including OAuth token refresh and custom signing, can be built exactly as the API needs it. | Partial The protocol defines authorization for HTTP transports, but scoping each agent's credentials and tying calls to a person is yours to design. Check: Model Context Protocol specification |
| Error handlingEdge: Hand-written SDK | Solid Error types can be designed with care, but keeping them in step with every documented error response is manual work. | Partial Tool errors are returned to the agent as results it can read; how useful they are depends on the server. Check: Model Context Protocol specification |
| MaintenanceEdge: MCP server over your API | Weak Every new endpoint, field and deprecation is hand work in every language, and the SDKs drift from the API when that work slips. | Partial Tool definitions must track the API. Generating them from the same API description keeps them in step; writing them by hand does not. |
| MCP readinessEdge: MCP server over your API | Weak A hand-written SDK does nothing for agents on its own. An MCP server is a separate project to build and keep in step. | Strong It is the MCP interface: agents discover the tools and call them directly. Check: Model Context Protocol specification |
The verdict, and when to ignore it
Too close to call: Hand-written SDK 10, MCP server over your API 9. Hand-written SDK takes auth handling and error handling. MCP server over your API takes maintenance and mCP readiness. Even on typing.
Pick Hand-written SDK when
Your callers are developers building integrations, and agents are not yet calling your API.
Pick MCP server over your API when
Agents in tools like coding assistants or chat clients are already trying to call your API, and you want them to use well-described tools rather than guess at endpoints.
modelcontextprotocol.ioMore matchups
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No SDK (raw HTTP) vs hand-written SDK
Hand-written SDK wins, 9 to 2, over No SDK (raw HTTP).
Speakeasy vs OpenAPI Generator
Speakeasy wins, 15 to 10, over OpenAPI Generator.