performance_overview

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds that results are compared against a previous equal-length period, which is useful behavioral context about the output, but says nothing about rate limits, quota cost, or data-freshness/lag that matter for a Search Console analytics call.

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 short sentences with the substantive content first and no filler. The phrasing is telegraphic and lacks a verb, but nothing is wasted.

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 read-only reporting tool with a fully documented 5-parameter schema and no output schema, the description tells the agent what it receives (totals, comparison, daily series, top queries/pages). What is missing is routing guidance against the many overlapping performance siblings, which is the main decision an agent faces here.

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%, so all five parameters, including date formats and the days/start_date interaction, are already documented in the schema. The description's search_type note adds no meaning beyond the enum description already present, so 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 names the concrete outputs — totals vs the previous equal-length period, daily series, top queries and pages — so an agent knows exactly what resource shape it gets back. It does not distinguish itself from near-siblings like compare_periods, performance_query, or property_overview, which keeps it from a 5.

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?

The only usage direction is 'Use search_type=discover for Discover', which is a restatement of the enum documentation rather than a when-to-use rule. There is no guidance about when this overview is preferable to compare_periods or performance_query, despite those siblings existing.

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