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

Annotations already cover read-only, idempotent, and non-destructive semantics, so the bar is lower, and the description adds real value: 'No sign-in' discloses the auth requirement, and 'signed out, the moneylines only' warns that an unauthenticated call returns a reduced dataset. It doesn't mention rate limits or pagination, but the partial-data caveat is the important disclosure.

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?

One dense sentence with the key identifier and the returned fields front-loaded; nothing is wasted. The parenthetical '(Kalshi's chance; signed out, the moneylines only)' is compact but reads awkwardly and blurs two distinct facts.

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 needn't document return values, and annotations carry the safety profile, so what remains — identity of the resource, auth behavior, and the unauthenticated data reduction — is largely covered. The undocumented full/market_type parameters are the only notable hole.

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 50%, so half the parameters (full, market_type) are undocumented in both places. The description does reinforce the ref/game semantics ('game_ id, slug or words') and hints at ordering with 'moneylines first,' but it never explains the boolean full flag or how market_type overrides the default moneyline-first behavior.

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?

Names a specific resource (one game, keyed by game_ id, slug, or team words) and enumerates the instrument fields returned, which clearly distinguishes it from the plural sibling list_games. The verb is implicit rather than stated ('One game ... with every instrument'), so it's clear but slightly elliptical.

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?

'No sign-in' tells the agent this call is available without authentication, which is genuine usage context. However, it never states when to pick this over list_games, get_market, or get_instrument, nor any conditions or exclusions — usage is only implied.

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