Runtime state

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description must fully convey behavioral traits. It details the contents of the snapshot (position, size, direction, etc.) but does not explicitly state that it is read-only or non-destructive, nor does it mention performance implications or side effects. The 'snapshot' framing implies read-only, but it falls short of disclosing all behavioral characteristics.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, information-dense sentence that starts with a clear headline ('A structured snapshot of the headless VM right now') and then lists all components. There is no filler, and every listed item adds value. It is appropriately sized for the complexity of a rich state snapshot.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given that there is no output schema, the description must fully specify what the tool returns, and it does so comprehensively: targets, variables/lists, monitors, bubbles, pending question, thread count, and errors. It also states the intended use (assertions). For a zero-parameter tool, this is complete enough for an agent to call and interpret the result.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has zero parameters, and schema coverage is 100% (empty schema). According to calibration rules, a baseline score of 4 applies because there is nothing to explain about parameters. The description does not need to add parameter semantics; it correctly focuses on the output.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states a specific verb ('snapshot') and resource ('headless VM'), enumerating exactly what it captures (targets, variables, monitors, bubbles, etc.) and its intended use ('Assert against these rather than a screenshot'). It distinguishes itself from screenshot tools and other state-related siblings by focusing on structured data rather than pixels.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It provides clear context for when to use this tool ('Assert against these rather than a screenshot'), implying it is for verification/diagnosis instead of visual inspection. However, it does not explicitly mention alternatives like get_target for narrower state queries or when not to use a full snapshot. Thus the guidance is clear but lacks exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.