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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds that similar keywords and their volumes come back alongside the core metrics, but says nothing about quota/cost per call (likely relevant for a paid keyword API) or failure behavior.

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, no filler: the first front-loads what is returned and the scope, the second gives use cases. Every clause carries information an agent can act on.

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 two-parameter read-only lookup with full schema coverage and an output schema, the description is nearly sufficient: purpose, scope and data returned are clear. The remaining gap is sibling differentiation — nothing tells the agent why to call this versus lookup_keywords.

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 coverage is 100% and both parameters are documented in-schema (including the ISO country pattern and default 'us'). The description only reinforces cardinality ('one keyword in one country'), adding little beyond what the schema already provides, so 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 specific verb (get) and resource (Google monthly search volume, CPC, competition, similar keywords) with scope 'one keyword in one country'. The 'one keyword' phrasing implicitly contrasts with the plural sibling lookup_keywords, but the alternative is never named explicitly.

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 concrete usage contexts — keyword research, sizing demand, comparing topics, picking SEO/content targets — so the agent knows the intent. It offers no exclusions and never says when to prefer the batch sibling lookup_keywords instead, which is the main missed routing cue.

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