MCP Server — Stack

Technology landscape as of 2026-10-10. Knowledge cutoff May 2026.

Selection criteria

The choice is a library plus a deployment shape, and the deployment shape constrains more than the library does.

• Deployment model. Whether the server runs as a short-lived child process on the caller's machine or as a long-lived network service. This decides authentication, credential custody, scaling, and who can reach the backing system.
• Concurrency behaviour. Whether one slow request blocks the process, since many servers are written as simple synchronous handlers and then deployed where they receive parallel calls from a single agent turn.
• Streaming and progress. Whether the library supports emitting incremental progress for long operations, which is the difference between a client waiting usefully and timing out.
• Session handling. Whether session identity, resumption after a dropped connection, and eviction are provided or left as an exercise, and whether the provided behaviour survives horizontal scaling.
• Surface authoring ergonomics. How declarations are written — decorators over functions, explicit schema documents, generation from an existing interface description — and whether the resulting descriptions can be edited for a model reader without editing code.
• Per-caller scoping. Whether the library makes the authenticated caller available to the handler, so the advertised surface and the backing call can both depend on it.
• Testability. Whether the surface can be exercised without a live client, so description and schema changes can be covered by ordinary tests.

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