Architecture · July 16, 2026 · 8 min read
MCPO vs Streamable HTTP: choosing the right interface for Kavach
The biggest misunderstanding is that MCPO and Streamable HTTP solve the same problem. They do not.
Think of MCP as a language. stdio and Streamable HTTP are two ways to speak that language; MCPO is a translator that exposes MCP tools as a conventional REST/OpenAPI API.
Streamable HTTP still requires the client to understand MCP. MCPO lets any HTTP client consume the capability without implementing MCP.
Different problems, different consumers
With Streamable HTTP, a client speaks the MCP protocol over HTTP. It must initialize a session, discover tools, send JSON-RPC requests and handle MCP responses. That is exactly what AI-native clients such as Claude, ChatGPT, Cursor and VS Code are built to do.
With MCPO, the same capability is presented as ordinary HTTP endpoints. A Java application, Python script, browser, API gateway, Postman collection or curl command can use it without knowing MCP exists.
| Aspect | stdio MCP | Streamable HTTP MCP | MCPO |
|---|---|---|---|
| Transport | stdin / stdout | HTTP | HTTP |
| MCP protocol | Yes | Yes | No — REST/OpenAPI |
| Client must understand MCP | Yes | Yes | No |
| curl / Postman | No | No | Yes |
| OpenAPI docs and SDKs | No | No | Yes |
How this maps to Kavach
Suppose Kavach exposes provider.list, evaluation.submit and job.status. An MCP client calls a discovered tool using a protocol message such as tools/call. A REST client calls a resource directly—for example, GET /provider/list or POST /evaluation/submit.
Neither is inherently better. The choice follows the consumer: AI assistants benefit from native MCP, while enterprise services and integration tooling benefit from REST conventions, OpenAPI documentation and generated SDKs.
The practical recommendation
If AI assistants are a first-class integration target, Kavach should expose a native Streamable HTTP MCP server. Since Kavach owns the server, there is no need to translate its own protocol through an adapter.
MCPO remains valuable as an optional compatibility layer for REST-only environments, or when a team has an existing stdio-only MCP server and wants to make it available to conventional HTTP consumers. Supporting both gives each client the interface it already understands.