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

With no annotations provided, the description carries the full disclosure burden but provides minimal behavioral context. It doesn't indicate whether this is read-only (implied by 'gets' but not explicit), what the output structure looks like, or how the 'severity' ranking (referenced in the metric parameter) is calculated.

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 single-sentence description is front-loaded with a clear verb and contains no wasted words. However, at only 9 words for a 13-parameter tool with complex filtering capabilities (date ranges, device types, pagination), it borders on underspecification rather than optimal conciseness.

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 the rich parameter set (13 params including time ranges, device filters, page groups, and statistical measures), the description is incomplete. It mentions none of these filtering capabilities and provides no hint about output format since no output schema exists.

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%, providing a baseline of 3. The description adds no parameter-specific context beyond the implicit mention of 'browser' as a dimension, nor does it explain parameter interactions (e.g., how daysBack/daysTo work with the default '8 days ago' behavior).

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 tool retrieves performance metrics with a browser-based breakdown, distinguishing it from siblings like 'get_page_performance_breakdown_by_country'. However, it uses the generic verb 'Gets' and doesn't specify that these are Core Web Vitals (LCP, INP, CLS, etc.) despite the schema revealing these specific metric types.

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 prefer this browser-specific breakdown versus the generic breakdown or country-based breakdown. No mention of prerequisites (beyond the required domain) or common use cases for browser-level analysis.

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