get_page_metrics

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

With no annotations provided, the description carries full responsibility for disclosing behavior. It only says 'get layout metrics', implying a read operation, but does not mention any side effects, prerequisites, return format, or whether it requires a live page. This is a significant gap for a tool that likely has some browser-side context requirements.

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, clear sentence with no unnecessary words. It is appropriately sized for a tool with one optional parameter, but it may be too terse to fully convey the purpose. Still, it is structurally well-organized and front-loaded with the verb.

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 and the tool is relatively simple, the description should at least hint at what 'layout metrics' includes and when to use this tool. It does neither, leaving the agent to guess the return value and applicability. While the low complexity reduces the burden, the lack of any context beyond the verb phrase makes it incomplete.

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 schema already provides 100% coverage for the only parameter (tabId with description 'Tab ID (optional)'). The tool description adds no additional semantic detail about the parameter, so it neither enhances nor detracts from the schema. 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 clearly states the verb 'Get' and the resource 'layout metrics of the page', making it distinct from sibling tools like get_html or get_accessibility_tree. However, 'layout metrics' is somewhat ambiguous—it doesn't specify whether these are dimensions, positions, or visual layout data. Still, it conveys the core action and object.

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?

No guidance is provided on when to use this tool versus alternatives or in what context (e.g., after page load, for a specific element). The description merely states what it does, leaving the agent to infer usage. There are no exclusions or alternative tool references.

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