Function call_operation 

pub async fn call_operation(
    endpoint: &EndpointRecord,
    config: &Config,
    auth_manager: &mut AuthManager,
    operation_id: &str,
    args: Value,
    request_override: Option<&RequestCredentials>,
) -> Result<Value>

Validates arguments against the input schema, injects the active auth strategy’s credentials, executes the live HTTP request, and validates the response against the output schema before returning it — PRD §1.5’s call pipeline (architecture.md’s 4-step call pipeline), protecting the calling agent from upstream API drift.

Takes an already-looked-up EndpointRecord rather than a Connection and an operation_id to look up itself: rusqlite::Connection isn’t Sync, so a &Connection held across this function’s .await points (the HTTP call) would make the caller’s future non-Send — a hard requirement for #[tool] methods (Story R6). Callers look the endpoint up (a synchronous, Connection-scoped step) before calling this function, not inside it.