Per-run dynamic headers enable secure multi-tenant MCP integrations

MCPTools and MultiMCPTools now support a header_provider callback to generate request headers at run time. This enables per-user and per-tenant authentication without custom plumbing, supports short-lived credentials, and simplifies compliance with enterprise security standards.

Details

Issue per-run, per-user tokens without forking or duplicating tool definitions
Reduce integration overhead for multi-tenant deployments and token rotation
Works across multiple MCP endpoints with consistent behavior

Who this is for: SaaS platforms and internal developer platforms that need strong isolation and policy-driven auth for MCP-based integrations.