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

Annotations already declare readOnly/idempotent/non-destructive, and the description still adds material context beyond them: API-key requirement, per-tier rate limiting and row caps with concrete numbers, and the important empty-case semantic that count=0 with empty rows is not an error. That empty-result disclosure is exactly the kind of behavioral detail agents otherwise misread as failure.

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?

Front-loaded with purpose, then constraints, then return shape, then routing -- a sensible order. It runs long, and the tier cap appears in both the description and the schema, but with no output schema the inline return-shape enumeration largely earns its space.

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 exists, so the description compensates by enumerating the return object, row fields, odds format, and the empty-day behavior. For a read-only 3-param flatten query, an agent has everything needed to call and interpret it.

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%, so stat, limit, and sport are already fully documented including the tier cap on limit. The description's tier-cap recital duplicates the schema rather than extending it; the American-odds/null details describe output fields, not the three input parameters. 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 -- 'Flatten every active player prop across all of today's games for a sport into a single list' -- with explicit scope (market-wide, cross-game, single sport). An agent can distinguish it from get_game_props and find_player_props without opening the schema, since those siblings are named directly.

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?

Contains an explicit positive trigger ('use scan_props when you need a broad cross-game market view') and an explicit exclusion block routing to get_game_props when an eventId is known and find_player_props for a single player. Both when-to-use and when-not-to-use are covered.

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