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

Goes well past the annotations: it names the external dependency (Google PageSpeed Insights), discloses expected latency (10-20 s, max 25 s), explains the CrUX field-data branch as conditional, and gives the LCP threshold. The latency and conditional-data notes are exactly the operational context annotations cannot convey.

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?

Three tight sentences, front-loaded with the action and source, then outputs, then timing. No filler and no repetition of the title.

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?

No output schema exists, and the description compensates by listing the returned scores, LCP, and optional field data. Combined with the latency note, an agent has enough to call it and set expectations; only the response shape (units, field names) is left unspecified.

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?

With a single parameter at 100% schema description coverage, the schema already documents the accepted domain/URL format. The description adds no extra syntax or format guidance beyond what the schema provides, so baseline 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?

States a specific verb and resource ('Mide con Google PageSpeed Insights la portada de una web en un celular simulado') and enumerates exactly which metrics come back. It does not name or contrast with the sibling revisar_visibilidad_ia, though the domains differ enough that confusion is unlikely.

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?

Usage is implied rather than stated: the description makes clear this is a mobile-only, homepage-only audit, which implicitly scopes when it applies. There is no explicit 'use this when / don't use this when' and no mention of the alternative tool for other kinds of checks.

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