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

Annotations already declare readOnlyHint=true, so safety is covered and the description usefully adds the entitlement requirement ('Pro keys only'). It says nothing about tie-breaking, score scale, or which universe is ranked, which matters for a ranking tool with no output schema.

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 short, front-loaded sentences with no filler; the access restriction is appended rather than buried. Slightly telegraphic, but nothing is wasted.

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?

For a low-complexity, three-parameter read-only tool with full schema coverage, the definition plus annotations plus schema are nearly sufficient. The remaining gap is what 'top pick' is drawn from and how ties or insufficient coverage are handled.

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%, with both enums fully documented (side, horizon) and limit bounded 1-10 default 5, so the schema carries the parameter burden. The description only restates the side semantics already in the enum, adding no format or default detail beyond it — baseline 3.

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 and resource ('Get ... stocks') with a clear scope qualifier ('highest- or lowest-scored ... for a horizon'). It implicitly distinguishes itself from get_all_scores and get_stock_score by returning a ranked subset, though it never names those siblings.

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?

'Pro keys only' is a useful eligibility condition, so an unentitled agent knows to stop. However, there is no explicit guidance on when to prefer this over get_all_scores or get_stock_score, leaving the agent to infer the ranking-vs-raw-scores distinction.

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