This record as markdown: /tools/io-github-dave-london-npm/tsc.md
What tsc does on Npm
AI agents invoke tsc to trigger actions in Npm. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
Why tsc is rated High
This tool executes the TypeScript compiler (tsc) as an external process. While its primary purpose is compilation/type-checking and it returns structured diagnostics, it runs an external command whose effects depend on arguments (e.g., it could emit output files, overwrite build artifacts). This places it in the Execute category.
From the tool's definition Runs the TypeScript compiler
Attacks that exploit this kind of access
The rule that runs tsc safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Npm, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For tsc, this is the rule to start with:
tsc stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Npm, apply this rule, and every tsc call is checked against it from then on.
Questions about tsc
Runs the TypeScript compiler and returns structured diagnostics (file, line, column, code, message). It is categorised as a Execute tool in the Npm MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Npm MCP server in PolicyLayer and add a rule for tsc: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Npm. Nothing to install.
tsc is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the tsc rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for tsc. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
tsc is provided by the Npm MCP server (Dave-London/Pare). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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