get_performance_summary

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description adds genuine behavioral context beyond them: the result is scoped to a single property and benchmarked against the previous period of equal length, which shapes how results should be interpreted. It omits auth/rate-limit details and return format, but that is a minor gap given the annotation coverage.

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: purpose first, then usage condition, then sibling alternatives. No redundancy and every sentence earns its place.

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 summary tool with no output schema and annotations carrying the safety profile, the description is largely complete: it conveys scope, comparison semantics, and routing. Return shape is not described, but with no output schema the agent could not get that from structured fields anyway.

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 siteUrl, period, and searchType are fully documented in the schema with enums and defaults. The description reinforces 'one property' and 'named period' but adds no syntax or format detail beyond the schema, making the baseline 3 correct.

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 (summarize) and resource (clicks, impressions, CTR, average position for one property), plus the distinguishing scope of comparing against the prior period. It explicitly names the siblings it is not (compare_periods, get_search_analytics), so an agent can differentiate without opening a schema.

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?

Gives an explicit trigger (user asks how search traffic is doing over a named period such as the last 28 days) and routes to alternatives with their own conditions: compare_periods for two named date ranges, get_search_analytics for raw rows. Nothing is left to inference.

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