1,509 MCP audit log rows, zero refusals: dev discovers permission checks never hit the audit trail
QuanTradin · reddit · 2026-10-03
The creator of Quantradin, an MCP-driven paper trading desk, found something unsettling: 1,509 audit log rows since Aug 19 (245 backtests, 6 bot deployments in the last 30 days via agent keys) contain not a single refusal.
Two explanations fit the zero:
- No agent ever hit a wall — implausible, since read-only keys shipped Sep 25 that can look and pause but can't open trades or start bots
- Permission checks fire before the audit write: the 403 returns before code that writes the row runs, so the log records what succeeded, not what was attempted. He bets on this one.
That undermines the core pitch of credential scoping: scoped access should show what the scope stopped, and a log of only yeses can't. The fix: write a row before the permission check, fill the outcome after (allowed / refused with reason / errored). He hasn't run the confirming test yet, and asks anyone running MCP servers with permission layers: do you log at the gate or at the tool — and have you ever caught a refusal that left no trace?
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