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 genuinely new context: the 2-credit cost and the fact that Champions League returns one table per group or for the league phase, both of which affect invocation planning.

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?

One dense, front-loaded sentence plus a short qualifier and the cost note. The field enumeration is long but every item earns its place by telling the agent what it will actually receive.

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, a full output schema, and 100% parameter coverage, the description only needed to supply cost and the UCL edge case — both are present. Nothing an agent needs to call this correctly is missing.

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 the baseline is 3, but the description adds real meaning about the 'ucl' enum value: results are structured per group or as a single league-phase table rather than one flat table. It also frames 'season' as the table's season, reinforcing what the schema already documents.

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 resource (season's league table) and enumerates the exact columns returned — rank, played, won, drawn, lost, goals, goal difference, points, notes, home/away records, form. This clearly separates it from stat-oriented siblings like get_team_stats or get_leaders, though no sibling is named explicitly.

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 opening 'Use for a season's league table' is a direct usage cue and the UCL grouping note tells the agent what to expect per competition. However, there is no when-not guidance and no reference to an alternative tool for related needs (e.g., per-team stats or ratings).

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