Merge pull request #20 from Joffref/majoffre/add-mcp-transport-comparison

Add MCP Hosting WG Transport comparison document

Author: evalstate

wg/hosting/research/mcp-transport-comparison.md

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+# 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 |