sourcemap_lookup
Resolve generated code position to original source (default), or — when originalSource is supplied — resolve original source:line:column back to the generated position. Supports indexed (sectioned) source maps transparently.
This record as markdown: /tools/io-github-vmoranv-jshookmcp/sourcemap-lookup.md
What sourcemap_lookup does on Jshookmcp
AI agents call sourcemap_lookup to retrieve information from Jshookmcp without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why sourcemap_lookup is rated Low
Tool queries source map data without creating, modifying, or deleting any code or files.
From the tool's definition Resolve generated code position to original source, lookup, no modification
Attacks that exploit this kind of access
The rule that runs sourcemap_lookup safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Jshookmcp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For sourcemap_lookup, this is the rule to start with:
sourcemap_lookup is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Jshookmcp, apply this rule, and every sourcemap_lookup call is checked against it from then on.
Questions about sourcemap_lookup
Resolve generated code position to original source (default), or — when originalSource is supplied — resolve original source:line:column back to the generated position. Supports indexed (sectioned) source maps transparently. It is categorised as a Read tool in the Jshookmcp MCP Server, which means it retrieves data without modifying state.
Register the Jshook MCP server in PolicyLayer and add a rule for sourcemap_lookup: 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 Jshookmcp. Nothing to install.
sourcemap_lookup 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 sourcemap_lookup 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 sourcemap_lookup. 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.
sourcemap_lookup is provided by the Jshook MCP server (@jshookmcp/jshook). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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