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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description's one genuine addition is the data-freshness caveat ('usually 2–3 days behind'), which affects how an agent interprets recency. It says nothing about rate limits, backfill limits or defaults for the period.

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?

Two sentences, front-loaded with what the tool returns and closing with the freshness caveat. No filler, no restatement 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?

For a 12-parameter read tool with no output schema, the description covers the returned surface and the one non-obvious behavioral trait (reporting lag). Defaults for date_range and the interaction between date_range and start_date/end_date are left entirely to the schema, which is a minor residual gap.

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 83% schema description coverage, the schema already explains site, detail, country, language, search_type and the *_contains filters. The description adds only the comparative framing ('vs the previous period'), which signals that a prior-period baseline is computed rather than requested as a parameter.

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 resource (organic Google Search performance for a site) and enumerates the metrics returned (clicks, impressions, CTR, average position) plus the two list sections. The only gap is sibling differentiation: it does not say how it differs from gsc_queries, gsc_pages or gsc_breakdown, even though it claims to include 'top queries and top pages' itself.

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: an agent can infer this is the entry point for an organic search overview, and the schema's detail parameter carries the summary-vs-full decision. There is no explicit when-to-use or when-not-to-use, and no pointer to the sibling tools that drill into queries or pages.

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