StackOne ships Tool Policies: fine-grained guardrails for MCP tool calls
afp-media · reddit · 2026-10-17
StackOne (poster is an employee) launched Tool Policies: every MCP tool call through its gateway is checked on the way in and out, so agents can get write access without getting access to everything.
- Example rules: block every tool matching delete for a group like contractors with one rule; allow payments between $25–$500 and stop bigger ones; a plain-language rule like "Is this compensation?" hides salary across HR systems with different field names; redact PII on inputs and outputs using a model they built.
- Fixed rules compile to Cedar, and each rule can run in Monitor mode first so you see what it would have blocked before enforcing.
- Live now, with the author answering questions in the thread.
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