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

Annotations already establish read-only/idempotent/open-world, so the bar is lower. The description adds genuinely useful behavior the annotations cannot: that it is a free-tier endpoint (quota context) and, critically, how to interpret a low events count as 'not posted on every game yet' — a data-freshness caveat. It doesn't mention pagination or row limits, so not 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?

The core behavior is front-loaded, followed by a return-shape clause and illustrative use cases; every sentence carries information. The 'Useful for' examples are slightly long but earn their place by disambiguating a niche coverage concept.

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 no output schema, the description responsibly describes the return payload (game count plus per-book game_lines and props entries with {market, period, events, markets, last_update}), so the agent knows what to expect. The remaining gap is that the periods parameter and the exact response envelope are left to the schema, but nothing essential for correct invocation is missing.

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 100% (days 1-7 default 3, periods boolean, sport_key examples), so the schema carries parameter meaning. The description only echoes the 'next N days' dimension and never explains the periods flag or its default, adding little beyond the schema. Baseline 3 applies.

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 resource and scope ('every market each book is pricing on a sport's games in the next N days'), which is a distinct concept from siblings like propline_get_history_coverage or propline_list_event_markets. The verb is implied ('returns', 'every market...') rather than front-loaded, but the agent can still identify what it gets back.

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?

Concrete use cases ('which books have NFL player props posted', 'does FanDuel price this market yet') make the selection context clear. However, it names no alternatives or explicit when-not conditions versus propline_get_history_coverage or propline_list_event_markets, so the routing guidance is contextual rather than exhaustive.

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