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 safety profile is covered. The description adds valuable behavioral context beyond annotations: billing per returned data row at $0.72, a 20-row cap, that 4xx/5xx responses are not charged, and that the response is semicolon-delimited text. This is exactly the kind of cost and format disclosure that helps an agent anticipate consequences.

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 with no filler. The core purpose is front-loaded, followed by the most decision-relevant operational details (billing, row cap, error charging, response format). Every sentence 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?

The tool has an output schema, so return values need not be described. The description covers purpose, cost, row limit, error billing, and response format. The only minor gap is that it doesn't explain the 'domains' comparison spec syntax, but the schema already does that with a clear example. For a read-only, idempotent tool with full schema coverage, this is nearly complete.

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 100%, so the schema already documents both parameters. The description does not add parameter-level detail beyond the schema, but it does clarify the output is semicolon-delimited text, which indirectly helps interpret the 'domains' parameter. Baseline 3 is appropriate because the schema carries the parameter documentation burden.

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 states a specific verb and resource: 'Cross-domain keyword position comparison across up to 5 domains.' This clearly distinguishes it from sibling tools like get_semrush_domain_organic_keywords (single-domain keyword lists) and get_semrush_organic_competitors (competitor discovery). It doesn't explicitly name a sibling, but the scope is clear enough.

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 for comparing keyword positions across domains, but it does not explicitly state when to use this tool versus alternatives like get_semrush_domain_organic_keywords or get_semrush_organic_competitors. The billing note gives a practical constraint (cost per row), which helps an agent decide whether to call it, but there is no explicit when/when-not guidance.

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