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

Annotations declare readOnly, openWorld, idempotent, and non-destructive hints, but the description adds crucial behavioral context beyond these: billing per returned row at $0.18, up to 20 rows, 4xx/5xx not charged, and response as semicolon-delimited text. This transparency is key for agents to manage costs and parse output.

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 description is two sentences, front-loaded with the primary function in the first sentence and key operational details (billing, limits, format) in the second. No filler or redundancy; every word 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?

With only 2 parameters, an output schema, and annotations covering safety, the description is nearly complete. It adds billing, row limits, and response format, which are essential. Minor gap: it doesn't mention behavior on empty results, but the output schema likely covers return structure. Overall sufficient for correct invocation.

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 covers 100% of parameters: phrase (with URL-encoding guidance) and database (with default). The description adds no extra parameter semantics beyond what the schema already provides. Baseline 3 is appropriate because the schema carries the full burden, and the description does not enhance it.

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 clearly states a specific function: 'Broad-match and alternate keyword variants for a seed phrase, with volume and CPC.' This verb-resource-output combination distinguishes it from siblings like get_semrush_domain_organic_keywords or get_semrush_question_keywords, which target different data types.

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 implies usage when a seed phrase is available and broad-match variants are needed, but it does not explicitly name alternatives or state when not to use this tool. Sibling tools exist for domain-based, paid, or question keywords, yet no routing guidance is provided.

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