Gate the Statement, Not the Tool Name

The original safety gate on the Dolt-over-MCP plugin tried to keep a Claude Code agent harmless by excluding "history-affecting tools" from its MCP grant. It was the wrong granularity, and it did nothing. MCP exposes the entire database through one tool — query / exec — and that tool carries every SQL verb. SELECT rides it. So does CALL DOLT_PUSH , CALL DOLT_RESET('--hard') , DROP DATABASE , and CALL DOLT_BRANCH('-D', 'main') . Excluding "dangerous tools" from the grant accomplishes nothing, because the dangerous verbs live inside the one tool you already granted. The destructive operations were never separate tools to exclude. This is the reframe the whole Phase 0 hardening pass turned on: a tool-name allowlist is meaningless for any tool that carries a sub-language. SQL is a sub-language. So is the shell behind a Bash tool. So is anything behind an eval . If the tool can run arbitrary statements in some grammar, the only boundary that means anything is one that reads the statement. It is the move from tool-name allowlisting to capability-based security: the grant stops being "you may call the query tool" and becomes "you may run these statement classes inside it." Why not just allowlist the safe tools? Because there is exactly one tool, and it is not safe or unsafe — it is whatever statement you hand it. You cannot partition a single door into a safe door and a dangerous door by naming. The same logic kills the next-obvious fix: a denylist of dangerous verbs. Blacklist DOLT_PUSH , DOLT_RESET , DROP ... and miss DOLT_REBASE , or the proc Dolt ships next quarter, or a CALL whose name your regex didn't anticipate. A denylist is only as good as your imagination on the day you wrote it. The fix inverts that. You add safety by enumerating what is safe, not by blacklisting what is dangerous. Anything you cannot positively classify as safe is treated as the most dangerous thing it could be. Default-deny the unknown. It's least privilege applied to a grammar: the agent get