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

Annotations declare a mutation (readOnlyHint=false), non-destructive, and idempotent. The description adds valuable behavioral context: enabling triggers a real weekly email only when meaningful changes exist, null reverts to account email, and partial-update semantics. It explains the side-effect (email) that annotations do not capture, and it does not contradict any annotation.

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 three sentences with no fluff. It front-loads the action and purpose, then lists fields compactly, and ends with a critical user-confirmation note. Every sentence carries weight; nothing is redundant. It is efficient without being terse.

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?

Given four parameters (one required), a mutation with a meaningful side effect, and no output schema, the description covers the action, all field semantics, partial-update behavior, and the confirmation requirement. It does not describe the response format, but that is not required without an output schema. It is sufficiently complete 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?

With 100% schema coverage, the baseline is 3, but the description enriches each parameter: defaults for enabled (off) and move_threshold (5), a numeric range (1-50), and explicit null behavior for email_override. It also clarifies partial-update meaning ('Only the fields you pass change'). This goes well beyond the schema's terse descriptions.

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 opens with a specific verb ('Update') and a precise resource ('rank-change alert settings for one RankParse website'). It enumerates the exact fields affected (digest enable/disable, move threshold, email override), and the contrast with the sibling 'get_rank_alert_settings' makes the read/write distinction obvious. The purpose is unambiguous and differentiates from other 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?

The description provides clear operational guidance: 'Only the fields you pass change' and 'Confirm with the user before enabling' – the latter explicitly warns about a side effect that should gate usage. It does not name alternatives explicitly, but the sibling set makes the read/write split clear. It could be enhanced by stating when not to use it, but the current guidance is solid.

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