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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description still adds real value by disclosing the 2-credit cost, the minimum-match filter, the active_since default, and the shared-endpoint league:'wta' quirk. It doesn't discuss result size or pagination beyond the limit.

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?

Dense and front-loaded: purpose first, then filters, then routing, then cost. It's telegraphic and slightly compressed, but every clause carries information, with no filler.

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 needn't be described; the description covers sorting, filters, defaults, and credit cost. Enough for an agent to call it correctly, with only minor gaps around surface enumeration and the atp/tennis naming mismatch.

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 100%, but the description goes beyond it by explaining the atp/wta tour concept and the mapping to league:'wta' for the shared endpoint, which the schema alone doesn't convey. Minor note: the description lists surfaces as hard/clay/grass while the schema also allows carpet.

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 the resource precisely ('our Elo ratings'), the sort order ('highest first'), and the two modes (overall or per-surface). This clearly separates it from get_rankings, which covers official rankings rather than Elo ratings.

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?

Explains eligibility (a rated match since active_since, at least 10 rated matches) and the tour/league routing rule. It gives clear usage context but never explicitly says 'use get_rankings instead for official rankings', so the alternative routing is left implicit.

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