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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds genuinely non-structured context: the call is free/no-credit and only replays data already paid for, which affects whether an agent should prefer it over a fresh fetch. It does not mention auth or rate limits, so not a 5.

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?

Front-loaded with the core value proposition and the free/no-credit framing, then the routing rule. Dense but every sentence carries information; the only mild padding is the rhetorical 'already bought and stored' clause, which still reinforces the usage point.

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 rich annotations, an output schema covering return values, and zero required parameters, the description supplies what remains: cost model, defaulting behavior for `target`, and the window meaning of `days`. Only `limit` is left unexplained, a minor gap for a low-risk read-only 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 three parameters. The description compensates for two of them ('days is the look-back window', 'leave target empty for every tracked domain') but says nothing about `limit`, leaving one parameter undocumented in both places.

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 (reads back) and resource (stored rank history measurements), then enumerates exactly what is returned: first/latest position, best ever, total change, full point series. It explicitly contrasts itself with the sibling seo_rank_tracker, so an agent can route without opening either schema.

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 an explicit when-to-use rule ('Call this BEFORE seo_rank_tracker when the question is "are we moving" rather than "where are we right now"') naming the alternative tool and the condition that selects it. Adds a defaulting instruction ('Leave `target` empty for every tracked domain'), leaving little to inference.

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