# hook_function Hooks a JavaScript function to log its calls, arguments, and return values. Useful for understanding how functions are used without setting breakpoints. Agent View of the PolicyLayer registry record for `hook_function`. HTML page: https://policylayer.com/tools/1600822305-js-reverse-mcp/hook-function ## Facts - Tool: `hook_function` - Server: Js Reverse (`1600822305/js-reverse-mcp`) — https://policylayer.com/tools/1600822305-js-reverse-mcp.md - Homepage: https://github.com/1600822305/js-reverse-mcp - Risk category: Execute (High risk) - Registry record: grade F, identity unverified - Server rate-limited: no - Parameters: 0 - Recommended policy verdict: Rate-limited ## Example call (MCP tools/call, JSON-RPC 2.0) ```json { "jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": { "name": "hook_function", "arguments": {} } } ``` ## Why hook_function is rated High Hooking a function requires executing code injection into the browser's JavaScript runtime. This is an active execution operation that modifies the runtime behavior of the target page. While described as non-intrusive (no breakpoints), it still runs injected code in the browser context, which could be misused to intercept sensitive data (credentials, tokens, PII) passed through hooked functions. From the tool's own definition: "'Hooks a JavaScript function' — injects instrumentation code into a running browser context to intercept function calls, arguments, and return values" ## Use case AI agents invoke hook_function to trigger actions in Js Reverse. 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. ## Recommended policy (PolicyLayer) Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Js Reverse: ```json { "version": "1", "default": "deny", "tools": { "hook_function": { "limits": [ { "counter": "hook_function_rate", "window": "minute", "max": 10, "scope": "grant" } ] } } } ``` ## Other tools on Js Reverse (92) - `clear_browser_cache` — Destructive — https://policylayer.com/tools/1600822305-js-reverse-mcp/clear-browser-cache.md - `clear_cookies` — Destructive — https://policylayer.com/tools/1600822305-js-reverse-mcp/clear-cookies.md - `clear_network_conditions` — Destructive — https://policylayer.com/tools/1600822305-js-reverse-mcp/clear-network-conditions.md - `delete_cookie` — Destructive — https://policylayer.com/tools/1600822305-js-reverse-mcp/delete-cookie.md - `delete_token` — Destructive — https://policylayer.com/tools/1600822305-js-reverse-mcp/delete-token.md - `remove_breakpoint` — Destructive — https://policylayer.com/tools/1600822305-js-reverse-mcp/remove-breakpoint.md - `remove_dom_breakpoint` — Destructive — https://policylayer.com/tools/1600822305-js-reverse-mcp/remove-dom-breakpoint.md - `remove_network_rule` — Destructive — https://policylayer.com/tools/1600822305-js-reverse-mcp/remove-network-rule.md - `remove_xhr_breakpoint` — Destructive — https://policylayer.com/tools/1600822305-js-reverse-mcp/remove-xhr-breakpoint.md - `add_network_rule` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/add-network-rule.md - `api_request` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/api-request.md - `batch_replay` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/batch-replay.md - `break_on_attribute_modified` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/break-on-attribute-modified.md - `break_on_node_removed` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/break-on-node-removed.md - `break_on_subtree_modified` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/break-on-subtree-modified.md - `break_on_xhr` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/break-on-xhr.md - `encode_protobuf` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/encode-protobuf.md - `evaluate_on_callframe` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/evaluate-on-callframe.md - `evaluate_script` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/evaluate-script.md - `hook_crypto_functions` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/hook-crypto-functions.md - `monitor_events` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/monitor-events.md - `monitor_eventsource` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/monitor-eventsource.md - `monitor_form_submit` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/monitor-form-submit.md - `monitor_input_changes` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/monitor-input-changes.md - `navigate_page` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/navigate-page.md - `new_page` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/new-page.md - `pause` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/pause.md - `replay_request` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/replay-request.md - `resume` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/resume.md - `set_breakpoint` — Execute — https://policylayer.com/tools/1600822305-js-reverse-mcp/set-breakpoint.md - …and 62 more: https://policylayer.com/tools/1600822305-js-reverse-mcp.md ## For agents This record is a snapshot. Live verdicts and the full registry: - Check every server in your MCP config at once: `npx -y policylayer stack` - Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md) - Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events` --- Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=1600822305-js-reverse-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/1600822305-js-reverse-mcp