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

Beyond the read-only annotations, the description discloses ordering ('oldest first'), grouping ('book by book'), the line_change computation, that capture counts vary by game and book, and a 10-credit cost — a real consumption constraint an agent cannot get elsewhere. It also flags the legal boundary on using price data, which is genuine behavioral context rather than restated safety hints.

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?

The purpose is front-loaded in the first clause, and every following sentence carries distinct payload: ordering, the line_change formula, capture variability, credit cost, and the usage restriction. Nothing is padded or repeated from the schema.

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 an output schema present, the description does not need to enumerate return fields, yet it still characterizes the payload (line, both prices, minutes before start) and explains the one derived field an agent would otherwise misread. Credit cost and the pricing-usage restriction close the remaining gaps for a read-only, single-player lookup.

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 schema already documents all four parameters including the market enum, so the baseline is 3. The description adds only indirect meaning — 'book by book' hints at what the optional bookmaker filter does — and adds nothing for game_id or player_id that the schema does not already carry.

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 states a specific verb and resource: showing how one player's prop line moved before a game. That separates it from get_line_movement (game-level lines) and get_prop_history in spirit, but it never names a sibling or states the boundary explicitly, so an agent must infer the split from the word 'prop'.

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 to see how one player's prop line moved before a game' gives a clear condition for selection, and the pricing disclaimer defines a hard scope limit on how results may be used. There is no explicit when-not or named alternative such as get_prop_history, which keeps it short of a 5.

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