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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower; the description still adds a real behavioral fact with 'No sign-in' and discloses the empty-result behavior of returning next_date. It does not describe pagination or cost of large day queries, but the added auth and empty-state context is genuine value beyond the annotations.

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?

Compact and front-loaded, with the primary listing behavior stated before the mode conditions. The telegraphic semicolon style ('priced', 'today (New York)') is dense enough that a first read can misfire, but no sentence is wasted.

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?

An output schema exists so return-shape detail is not required, and the description still conveys grouping-by-league and the moneyline percent unit. The only real hole is the unexplained 'full' flag, which leaves a mode of the call invisible to the agent.

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 75% and the description reinforces the date semantics ('today' is New York time) and the limit asymmetry (max 100 for a day, default 20 for a league), which is real added meaning. However, the 'full' boolean is undocumented in both schema and description, so one parameter is opaque in the only two places it could be explained.

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 (a day's games, or a league's upcoming games) plus what is returned (moneyline chance from Kalshi, grouped by league). It distinguishes its own two operating modes clearly, but never names sibling tools like get_game or list_markets, so the agent must infer the boundary itself.

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 usable routing logic: with a date you get that day's slate, with a league and no date you get that league's upcoming priced games, and an empty day points you to next_date. No explicit exclusions or named alternatives are given, which is the only thing separating this from a 5.

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