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

Annotations already cover safety (readOnly, idempotent, non-destructive), yet the description still adds real behavioral value: exact case-insensitive matching and the failure mode where an unresolved query returns up to 5 candidate suggestions. It could go further on how empty/no-data periods behave, but the error-path disclosure 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?

Front-loaded with the core purpose, then return shape, then matching semantics in three tight sentences. The trailing Portuguese fragment ("/ Série de uma query exata.") adds nothing for an English-reading agent and is the only wasted text.

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 14-parameter analytics tool with no output schema, the description covers what comes back (totals, comparison, series, counterparts) and the error path, which is the main ambiguity an agent would hit. Missing only a note on pagination/response size for high-cardinality counterparts, a minor gap given full schema coverage.

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 14 parameters are already documented in detail (defaults, enums, date fallbacks, brand semantics). The description only restates the query-matching rule and the optional single-page restriction, which the schema largely covers already. 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 concrete verb+resource with explicit scope ("Daily performance of ONE search query on the property, optionally on one page") and describes the returned shape (totals, comparison deltas, series, top counterparts). That scope alone distinguishes it from list-style siblings such as query_top_queries and get_page_performance.

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 "ONE query" emphasis implicitly tells the agent this is not a listing tool, and the exact-match/fuzzy-fallback rule explains what to expect on a miss. However, no sibling is named and there is no explicit when-to-use / when-not guidance (e.g. use query_top_queries to discover which queries exist first).

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