10 tools. 3 can modify or destroy data without limits.
3 write tools that can modify data. Rate limits recommended.
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Write operations (install, outdated) modify state. Without rate limits, an agent can make hundreds of changes in seconds — faster than any human can review or revert.
Execute tools (run) trigger processes with side effects. Builds, notifications, workflows — all fired without throttling.
Intercept sits between your agent and Npm. Every tool call checked against your policy before it executes — so your agent can do its job without breaking things.
npx -y @policylayer/intercept scan -- npx -y @paretools/npm install:
rules:
- rate_limit: 30/hour Prevents bulk unintended modifications from agents caught in loops.
audit:
rules:
- rate_limit: 60/minute Controls API costs and prevents retry loops from exhausting upstream rate limits.
The Npm server has 2 write tools including install, outdated. Set rate limits in your policy file -- for example, rate_limit: 10/hour prevents an agent from making more than 10 modifications per hour. Intercept enforces this at the transport layer.
10 tools across 3 categories: Execute, Read, Write. 7 are read-only. 3 can modify, create, or delete data.
One line change. Instead of running the Npm server directly, prefix it with Intercept: intercept -c io-github-dave-london-npm.yaml -- npx -y @@paretools/npm. Download a pre-built policy from policylayer.com/policies/io-github-dave-london-npm and adjust the limits to match your use case.
Starter policies available for each. Same risk classification, same one-command setup.
Set budgets, approvals, and hard limits across MCP servers.
npx -y @policylayer/intercept init