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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered; the description adds value by disclosing the return payload (difficulty scale, popularity, results count, autocomplete suggestions) in the absence of an output schema. If a schema existed, this disclosure would be redundant, but here it 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, zero filler, outputs front-loaded before the usage hint. 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 research tool with full schema coverage and complete annotation coverage, the description supplies what structured fields don't: the shape of the return value. The only shortfall is the unaddressed overlap with sibling keyword tools, which an agent must disambiguate on its own.

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% – query, store, and country each carry their own documentation including the ISO code format and defaults – so the schema does the work. The description adds no parameter-level detail beyond what the schema already states, making the baseline 3 appropriate.

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+resource (research a keyword and related terms) and enumerates the outputs (difficulty 0-100, popularity score, results count, autocomplete suggestions). Clear on its own, but it never distinguishes itself from close siblings like sonar_keyword_metrics or sonar_keyword_suggestions, several of which also return keyword metrics.

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?

"Use this to find keywords worth targeting" implies intent but names no alternative and gives no when-not condition, which is a real gap given the dense cluster of keyword tools (keyword_metrics, keyword_suggestions, keyword_rankings, app_keywords). Usage is only vaguely implied rather than routed.

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