MCP Tool
nova.eval
For page perception, diagnostics, and verifiable read signals, an agent uses this public tool to carry out the bounded step "Eval with DOM mutation". It separates target confirmation, intended state change, and verification after execution.
Canonical reference for a public MCP tool name.
- Type
- MCP tool
- Family
- JavaScript & Diagnostics
- Effect
- changes state
- Status
- Explained
- Path
- 30.2
Purpose
What this entry explains
What it does
nova.eval
An agent uses this tool to carry out the bounded step "Eval with DOM mutation". It belongs to page perception, diagnostics, and verifiable read signals; agents should combine it with current discovery, target awareness, and the visible result.
Use when
- Use this entry when an agent needs to carry out the bounded step "Eval with DOM mutation" for page perception, diagnostics, and verifiable read signals.
- Use it to understand the public tool name, its expected boundary, and the response signals to check.
- Use it before chaining follow-up tools so the next step is based on current evidence.
Reference Use
How agents should cite and apply this area
Examples are maintained at family level and use only public tool names or reference paths already present in the catalog.
Family example
A task in page perception, diagnostics, and verifiable read signals can trigger powerful execution and therefore needs target, approval, and result check before the step.
The agent starts with nova.eval, reads the current response or reference, and only then chooses the concrete next tool.
Current discovery, target, user control, warning signals, and result check come before execution.Contract
Inputs and important response fields
This page is a public reference. Agents and integrators should still read current MCP tool discovery before execution, because schemas can be gated by settings or version.
Inputs
expression
Content-bearing input. Treat user data and executable text as sensitive unless the purpose is explicit.
background
Public input field from the catalog source. Confirm the exact schema through current MCP discovery before execution.
Response fields
No fixed public response field is derived from the catalog source for this path. Use current tool discovery and the actual response before chaining the next step.
Safety
Boundary before execution
Can change browser, page, or workflow state. The target and expected result must be clear before execution.
Confirm the current target first, perform only the intended bounded action, and verify the resulting page or workflow state afterwards.
For humans, this entry names the browser or workflow state in page perception, diagnostics, and verifiable read signals that may change, so the action can be reviewed before and after execution.
High-Impact Review
Execution boundary and recheck hints
Review category: Eval/CDP/diagnostics
Run only on the currently confirmed target; expression, expected result, and visible context must be clear before the call.
False assumption: because a script is intended to read, the path is automatically harmless.
The user must be able to see which page is targeted and why code, CDP, or diagnostics are being run.
Before execution, check current discovery, target, expression, and stop signal; do not derive additional scripts from the result.
Abort or recheck if the target changed, the expression touches third-party data, or the response contains warnings.
Safety Axes
How this path can affect work
Axes are stable catalog signals for humans, agents, and LLM discovery. One path can carry several axes.
browser_state_change
Changes tab, navigation, focus, claim, scroll position, window state, or browser environment.
Confirm the target context visibly before execution and verify that the expected browser state was reached afterwards.high_impact_execution
Runs or prepares JavaScript, CDP, plugin code, auto-apply, or other powerful execution paths.
Explicitly confirm current tool discovery, target, scope, user control, and result check before execution.user_confirmation
Requires visible confirmation, target review, approval, or deliberate user control.
Do not proceed until the required confirmation is visible or unambiguous in the current context.