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 adds real value beyond them—result ordering ('strongest first'), the latest-by-default behavior, and a credit cost ('Costs 2 credits'). It omits return format details, but the output schema covers that.

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?

Three tight sentences, each earning its place: purpose and ordering front-loaded, then the Elo interpretation, then the cost. No redundancy or 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-value explanation is unnecessary; the description still provides sort order, temporal default, the interpretive Elo gap heuristic, and cost—everything an agent needs to call and interpret results correctly.

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%, so all three parameters are already documented in the schema. The description merely echoes the date default ('or as of date') without adding syntax, format, or behavior beyond the schema—baseline 3 is appropriate.

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 ('our club Elo ratings') plus ordering ('strongest first') and a temporal scope ('as of the latest match (or as of date)'). This clearly distinguishes it from sibling tools like get_standings and get_team_stats, which return different metrics.

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?

'Use for our club Elo ratings' gives a clear usage context, reinforced by the date-scoping note. However, it does not explicitly name alternatives (e.g., get_standings for table position) or state when-not to use it, leaving routing to inference.

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