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 meaningful context beyond that: the data is Bing's own (not a blended estimate), it is free via Bing Webmaster Tools, it returns week-by-week granularity, and it carries an interpretive caveat about not treating counts as total demand.

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, front-loaded with the purpose and data source before the caveat. Every clause carries information; the only mild redundancy is restating the Bing-ownership point. Appropriately sized for the tool's scope.

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?

With no output schema, the description must convey return values, and it does: search counts for the keyword, week-by-week breakdown, and related keywords with their counts. That covers what an agent needs to call and interpret the tool; only the exact date-range semantics and default handling are left entirely to the schema.

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 83%, so the schema documents most parameters (country, related, language, dates) already. The description hints at the date-period and related-keyword parameters ('in a period (week by week too)', 'related keywords') but adds no format or syntax detail beyond the schema, so the 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 resource ('keyword research') and verb-like action, and clarifies the data source as Bing's own counts with two concrete outputs (search volume over a period, week-by-week breakdown, and related keywords with counts). It clearly distinguishes itself from Google-based tools by emphasizing Bing data, but it never names the close siblings (keyword_volume, keyword_ideas, domain_keywords), so the agent must infer the distinction.

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 description gives an interpretation caveat ('use them to compare keywords against each other and to see trends, not as a keyword's total search demand'), which is useful guidance on how to use the output. However, it gives no when-to-use-vs-alternatives guidance, e.g., when to pick this over keyword_volume or keyword_ideas, leaving tool selection to inference.

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