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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the read-only safety profile is covered elsewhere. The description's sole contribution is cost transparency (usage-based billing, ~$0.005/request, account-specific settlement), which is genuinely useful but says nothing about data source behavior, batching limits implied by x-aisa-maxItems=20, or result freshness.

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?

The text is short, but it is boilerplate wrapped in HTML comment markers that consumes the entire description while conveying none of the tool's functional purpose. Brevity here stems from omission, not from disciplined editing.

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?

Although an output schema and rich annotations exist, the description omits everything an agent needs to select this tool over its many keyword-data siblings and to supply 'phrase'/'database' correctly. Pricing alone is insufficient for a 2-parameter, high-sibling-ambiguity tool.

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 0% for both parameters, and the description adds nothing about 'phrase' (multi-value, delimiter ';', max 20 items) or 'database' (which SEMrush database/region to query). With zero coverage on both sides, the agent is left to guess parameter meaning entirely.

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?

The description never states what the tool does. It contains only a billing/pricing notice ('Usage-based billing; Default request estimate: $0.005 USD'), so an agent cannot tell this retrieves SEMrush keyword difficulty scores, nor distinguish it from siblings like get_semrush_keyword_overview or the DataForSEO difficulty tools.

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?

There is no when-to-use guidance, no prerequisites, and no reference to alternatives such as post_dataforseo_labs_google_bulk_keyword_difficulty_live or get_semrush_keyword_overview. The only conditional text is about pricing, not invocation context.

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