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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered; the description adds real context beyond them — data sources (Kalshi, Polymarket as an international book), the "starting goalies checked first" precondition, the 10,000-season sim backing futures, and the "Free" cost note. It stops short of describing latency, rate limits, or failure behavior.

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 description is front-loaded with the trigger phrases and then moves through scope, output shape and market modes in three dense sentences with little redundancy. The em-dash and middle-dot notation (Market · Model · Fair) is compact but adds a small parsing burden.

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?

For a zero-required-parameter, read-only tool with no output schema, the description supplies the essentials: what the rows represent, the two data sources, and the market modes. The output format summary compensates for the missing output schema, though it does not describe row granularity or error cases.

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 baseline is 3; the description earns above that by explaining what each market value actually yields (goals = anytime and first-goal contracts; futures = Cup, conference and division markets), which goes beyond the schema's terser "player-goal contracts" and "Stanley Cup + season markets". It adds no detail on team or limit, but those are fully documented in the schema.

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 a specific resource (tonight's NHL games on Kalshi priced as Market · Model · Fair) and enumerates the market types, so an agent can tell it serves NHL betting-model comparisons. It does not use an explicit verb like "get" or "list", and sibling differentiation rests entirely on the word "NHL" rather than a named contrast with tools like nfl_edge.

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?

"Use for 'NHL predictions tonight' and 'Stanley Cup odds'" gives concrete trigger queries that map directly to the tool, and the market=goals / market=futures clauses clarify which mode serves which need. No exclusions or named alternatives are given, so an agent must infer when not to reach for it.

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