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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so safety is covered. The description adds valuable behavioral context beyond annotations: deterministic output, compact YAML format, low token cost, and suitability for deciding what to click or fill next. It stops short of describing pagination or size limits, but with an output schema present that is a minor gap.

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 three tight sentences with zero waste, front-loading the primary use case before stating the exclusion. Every sentence contributes directly to correct tool selection or invocation context.

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?

For a single-parameter read-only inspection tool with an output schema, the description provides everything needed: purpose, return format, cost characteristics, and the alternative to use for visual needs. No critical decision information is missing.

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?

Schema description coverage is 100%, and the sole session_id parameter is already well documented in the schema, including reuse semantics for cookies, login state, and page position. The description adds no parameter-specific meaning beyond the schema, so the baseline of 3 applies.

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 states a specific capability: returning the accessibility tree (roles, names, states) as compact YAML for understanding page structure. It clearly distinguishes this from browser_screenshot by contrasting semantic structure with visual layout/images, allowing an agent to choose without opening schemas.

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 gives explicit 'Use for' guidance and an explicit 'Don't use when' condition, naming browser_screenshot as the alternative for visual layout or images. The decision boundary between cheap structural inspection and visual inspection is unambiguous.

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