Index TypeScript declaration files from node_modules to enable symbol search in external dependencies. This tool scans node_modules for .d.ts files and indexes their symbols for fast searching.
AI agents call index_external_libraries to retrieve information from TypeScript MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs static analysis of TypeScript declaration files already present in the local node_modules directory. It reads .d.ts metadata to build an in-memory index for symbol search capabilities. There are no side effects, no code execution, no data deletion, and no external operations triggered.
From the tool's definition Tool description explicitly states it 'scans node_modules for .d.ts files and indexes their symbols for fast searching.' The verbs are 'scans' and 'indexes' which are read-only operations on static declaration files.
Documented attack patterns abuse exactly the kind of access index_external_libraries gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and TypeScript MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for index_external_libraries:
{
"version": "1",
"default": "deny",
"tools": {
"index_external_libraries": {}
}
}index_external_libraries is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Index TypeScript declaration files from node_modules to enable symbol search in external dependencies. This tool scans node_modules for .d.ts files and indexes their symbols for fast searching. It is categorised as a Read tool in the TypeScript MCP MCP Server, which means it retrieves data without modifying state.
Register the TypeScript MCP server in PolicyLayer and add a rule for index_external_libraries: 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 TypeScript MCP. Nothing to install.
index_external_libraries is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the index_external_libraries 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 index_external_libraries. 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.
index_external_libraries is provided by the TypeScript MCP server (mizchi/lsmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from TypeScript MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
3 TypeScript MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.