capture_surface_stats
Capture Android SurfaceFlinger stats and logcat for jank analysis (Layer 0 only). Returns janky frame counts, missed vsync, slow UI thread metrics, and filtered logcat entries from Choreographer, SurfaceFlinger, WindowManager, ActivityManager, InputDispatcher. Requires FLICKER_SERVER_URL and adb-...
This record as markdown: /tools/io-github-homenshum-nodebench/capture-surface-stats.md
What capture_surface_stats does on Nodebench
AI agents invoke capture_surface_stats to trigger actions in Nodebench. 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 capture_surface_stats is rated High
This tool executes adb commands against a connected Android device to collect runtime diagnostics (SurfaceFlinger stats, logcat entries). It triggers external operations whose effects depend on the device state and connection. It is not purely read-only since it actively invokes remote device instrumentation, placing it in Execute.
From the tool's definition 'Capture Android SurfaceFlinger stats and logcat for jank analysis' — triggers external operations via adb on a connected device, runs logcat capture and SurfaceFlinger stat collection
Attacks that exploit this kind of access
The rule that runs capture_surface_stats safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Nodebench, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For capture_surface_stats, this is the rule to start with:
capture_surface_stats 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 Nodebench, apply this rule, and every capture_surface_stats call is checked against it from then on.
Questions about capture_surface_stats
Capture Android SurfaceFlinger stats and logcat for jank analysis (Layer 0 only). Returns janky frame counts, missed vsync, slow UI thread metrics, and filtered logcat entries from Choreographer, SurfaceFlinger, WindowManager, ActivityManager, InputDispatcher. Requires FLICKER_SERVER_URL and adb-connected device. It is categorised as a Execute tool in the Nodebench MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Nodebench MCP server in PolicyLayer and add a rule for capture_surface_stats: 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 Nodebench. Nothing to install.
capture_surface_stats 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 capture_surface_stats 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 capture_surface_stats. 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.
capture_surface_stats is provided by the Nodebench MCP server (nodebench-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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