Keyword search volume & difficulty

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

Adds real behavioral context beyond the annotations: the tool costs credits, repeat queries of the same keyword set within a week are free, and difficulty is computed for the US when location is omitted. Annotations (readOnlyHint=false, destructiveHint=false) already cover the safety profile, so this is meaningful extra value.

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 dense sentences, front-loaded with what is returned, followed by when-to-use and the market/cost rules. No filler, and the cost caveat appears exactly where an agent needs it.

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 itself enumerates the returned fields and their sourcing (Keyword Planner vs DataForSEO Labs), plus the 10-keyword cap. An agent has everything needed to call and interpret it.

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% so the baseline is 3, but the description adds semantics the schema does not: the 'omit location_code for worldwide volume' behavior and the non-obvious US fallback for difficulty. That genuinely informs the location_code decision.

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 (keyword search volume & difficulty) and enumerates the exact metrics returned: volume, CPC, competition, 12-month trend, difficulty 0-100. It is unmistakably distinct from siblings like research_backlinks or gsc_queries.

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 triggering conditions ('user asks how often something is searched or how hard it is to rank', 'size a keyword before writing a page') plus the location_code decision rule. It does not name an alternative tool, but no sibling competes for this job, so the omission is minor.

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