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

Annotations already establish readOnly/openWorld/non-destructive, so the description's marginal value is in the operational details it does provide: sort order (clicks descending), pagination via start_row, and that ctr is a 0-1 fraction. It stops short of describing row-limit behavior or what happens when filters match nothing, but the added context is genuinely useful.

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 short sentences, front-loaded with the resource and metrics, then paging and unit caveats. No filler and nothing repeated from the schema.

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?

The output schema means return values need not be explained, and date-lag/format details live in the schema. However, for a 10-parameter tool with 60% coverage, the description leaves the aggregation and search-type semantics entirely to the schema, which is a noticeable gap for correct invocation.

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 60% schema coverage, several parameters (search_type, aggregation_type, data_state, row_limit) carry no meaning in the description at all. The description does clarify paging through start_row and the ctr unit, but it adds nothing about the aggregation/search-type choices that materially change results.

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?

Opens with a specific verb+resource ("Search performance from Search Console") and enumerates the exact metrics returned (clicks, impressions, CTR, average position) plus the available groupings. This clearly separates it from sibling tools like gsc_inspect_url or gsc_list_sitemaps, which do not retrieve performance rows.

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 only implied: the mention of groupings and "Omit for site totals" hints at how to shape a request, but there is no explicit when-to-use versus alternatives (ga4_run_report, seo_opportunities) and no stated prerequisites beyond the schema's site_url format note. An agent must infer the selection criteria.

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