Don't put secrets in MCP headers

Mcp-Method and Mcp-Name let gateways route without parsing JSON — great for ops. Terrible if you copy bearer tokens into custom headers that proxies log by default.

Source: Influzer.ai

MCP 2026-07-28 added header-based routing: Mcp-Method and Mcp-Name so gateways can meter and route without reading JSON bodies. That is a real ops upgrade for stateless HTTP.

The footgun: teams map bearer tokens, tenant secrets, or OAuth access tokens into custom headers “for routing.” Proxies and CDNs log headers by default — so credentials become log inventory.

Safe split:

Authorization — auth only, redact in logs
Mcp-Method / Mcp-Name — non-secret routing labels
Parameter headers — public routing keys only, never secrets

Why it matters: remote MCP is now normal HTTPS traffic. Your WAF rules are only as safe as your log redaction policy.

Full playbook (gateway checklist, reviewer questions, safe patterns): Don't put secrets in MCP headers. Pair with OAuth and the over-permission trap.