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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so safety is covered. The description adds things annotations cannot: a Pro-tier access requirement and an explicit non-recommendation guarantee ("never gives a pick"). It stops short of covering pagination or result-size limits for the board view.

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?

Two sentences, front-loaded with the usage trigger, then the return payload. It is dense but every clause maps to a distinct output or constraint. The long second sentence packs many return artifacts together, which slightly reduces scannability but wastes no words.

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?

There is no output schema, so the description carries the full burden of describing return values, and it does so thoroughly: upcoming lines, book-by-book odds and moves, averages, L5/L10/L20/season hit rates, model probability, over/under/push record against closing lines and alternate ladders, plus board/cheat-sheet contents. Both branches (player_id present or absent) are covered, along with the access prerequisite and the non-advisory nature.

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 parameter documentation is already complete and detailed (date format, stat code examples, game_id filter, player_id behavior). The description adds the useful cross-parameter semantic that omitting player_id switches the entire output shape to the board plus cheat sheet, but it does not add per-parameter detail beyond what the schema states. Baseline 3 applies.

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?

The description names the resource precisely (prop lines, hit rates, book-by-book odds, closing-line record, ladders) and distinguishes two operating modes: with player_id it returns that player's research; without it, the daily board and cheat sheet. No sibling tool (defense_vs_position, game_projection, tonight_slate, etc.) covers prop research, so the agent can route here unambiguously.

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?

Opens with an explicit trigger: "Use this when the user asks about a player's prop lines, how often he clears a line, book-by-book prices, or today's prop board." It also states a prerequisite (Keel Stats Pro) and a hard boundary ("Research only: it never gives a pick"). It does not name a sibling alternative for overlapping queries such as slate-level context, 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.