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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds the meaningful extra facts that the response is capped at the top 15 and that date omission resolves to the latest visible session.

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?

A single short sentence with the core behavior front-loaded and the default-behavior rule attached — no filler to trim.

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?

An output schema exists so return values need not be explained, and the date default is covered. However, for a 0%-coverage tool the undocumented market parameter and the lack of any routing to get_alpharank_history leave meaningful gaps.

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 coverage is 0%, so the description must carry parameter meaning; it does explain the null/omitted date behavior, but says nothing about the market parameter (default "us", max length 20) or what values it accepts, leaving half the surface undocumented.

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+resource ("Get AlphaRank top-15 for a session") and reveals the result shape (top-15). It does not explicitly differentiate itself from the sibling get_alpharank_history, leaving the boundary to be inferred from the name.

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 clause "omit date for the latest visible session" gives a concrete usage rule for the date parameter, but there is no guidance on when to call this versus get_alpharank_history or other signal siblings, and no mention of the market scope.

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