MCP Transports Pros/Cons

This document is intended as a preliminary proposal and does not represent an official statement for the MCP standard.
Date: Apr 18, 2025

This document aims to provide a basis for evaluating the inclusion of new standard MCP transports by listing the advantages and disadvantages of each.

STDIO Transport

Category	Pros	Cons
Client/Server Connection Management	Universal, language-agnostic subprocess APIs make spawning and wiring up stdin/stdout trivial.	Requires clients to manage lifecycle and crash recovery, adding complexity.
Observability	stderr separation enables clean logging without polluting protocol data.	Lacks out-of-the-box tooling for stream capture and correlation without custom adapters.
Authorization	Implicit local trust boundary via pipes means no exposed network port.	No built-in auth or ACLs; must implement custom authorization logic.
Scalability		Not suited for distributed or multi-tenant scenarios without an external dispatcher.
Complexity within a Large-Scale Architecture	Deterministic startup/shutdown simplifies orchestration for CLI-first tools	Integration with observability and service discovery tools requires additional adapters. Plus, the overhead of spinning a process per client is huge.

HTTP Stream Transport

Category	Pros	Cons
Communication	Simplify client-server communication Handles 90% of the MCP use case with tools/list and tool/calls
Deployment	Can be deployed on the cloud easily. Compatibility with serverless functions
Flexibility	Choose between two modes. Best of both worlds	Implementation complexity on the server side