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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is covered. The description adds a genuine behavioral constraint not in the annotations — that results are scoped to prematch events only and span all periods of a market. It omits response size/pagination behavior for what is potentially a large 'all lines' payload, keeping it short of a 5.

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?

Three tight sentences in a deliberate order: what it returns, when to prefer it over the sibling, then the prematch-only exclusion. No wasted words and the core purpose is front-loaded.

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 two-parameter read tool the routing and scope information is strong, and no output schema exists so return semantics must come from the description — which it partially supplies ('all spreads, or all totals, etc.'). The remaining gap is that parameter identity and allowed market_type values are left entirely to the schema.

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 0% for both parameters, so the description must compensate, and it does not: neither event_id nor market_type is named, and the enum values (money_line, spreads, totals, team_total) and the 'totals' default are never referenced. The phrases 'spreads'/'totals'/'handicap' loosely evoke the market concept but do not tie meaning to a specific parameter.

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 concrete action and resource: 'Every alternate line for ONE market of ONE prematch event ... across its periods.' It explicitly distinguishes itself from the sibling get_event_odds ('centred selection is not enough'), so an agent can route correctly without opening either schema.

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 explicit when-to-use ('when get_event_odds' centred selection is not enough — e.g. to find the price at a specific handicap') and a when-not ('prematch only; for live events use get_event_odds with response_format=detailed'). Both the alternative and the selecting condition are named.

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