# MCP Protocol Profile

## Supported revisions

- primary: `2026-07-28`;
- compatibility: `2025-11-25` and earlier revisions supported by ContextForge/SDK v2.

## Transports

- remote dataplane and connectors: Streamable HTTP;
- local bridge and tests: stdio;
- no custom WebSocket protocol.

## Server behavior

- explicit server identity and version;
- tool/resource list responses are cacheable only within correct project/client scope;
- structured outputs are validated against declared output schemas;
- requests and results include correlation metadata;
- maximum request body at or below 4 MiB;
- per-tool timeouts and output budgets are stricter than global limits;
- protocol errors are distinct from target-system errors.

## 2026 headers

Where available, `Mcp-Method` and `Mcp-Name` can support routing, metrics, and rate limits. They are hints from a validated protocol path, not the sole authorization input. Compatibility traffic may require bounded body parsing by trusted components.

## Durable work

Do not depend on MCP Tasks in v1. Use `operation_id` in the management domain and expose status through ordinary Hub APIs/resources when needed. Add a protocol adapter only after the official SDK supports the extension.

## Client bridge

A local bridge may translate stdio to remote HTTPS. It stores credentials in the local OS-protected environment/configuration and never prints tokens. The bridge is optional; native remote MCP is preferred.