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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely new behavioral context — access tiers and per-tier fact quotas (free 3, Creator 12, Pro/Publisher 30) — that an agent needs to predict results and errors.

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, front-loaded with what the tool returns, then modes, then limits. No filler; every clause carries information.

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?

No output schema, but the description conveys the return shape (plain sentences with stat, value, as-of date), both invocation modes, tier prerequisites and quotas. 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 baseline is 3. The description adds structure the schema doesn't state outright: that home and away are the game-mode pair, that kind defaults to matchup, and that entity modes need a paid tier, which helps an agent choose parameters correctly.

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 — 'checked sport-stat facts (plain sentences with the stat, value and as-of date)' — and delineates scope: one game (home+away) or, with Pro/Publisher, one player or team. 'Stats only: no prices, picks or chances' explicitly separates it from siblings like get_free_picks and get_predictions.

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?

Gives clear context: game mode vs player/team mode, plus the prerequisite that player and team require Storylines Pro or Publisher, and it points to get_storylines_games for team naming. It doesn't spell out explicit exclusions beyond 'stats only', which keeps it from a 5.

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