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

With no annotations, the description carries the full burden. It usefully discloses the return shape (line, over/under prices in American and decimal, status, move summary from open) and the 'current' freshness framing, but says nothing about read-only safety, whether live calls have latency limits, or pagination behavior beyond the schema's offset field.

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 sentences, zero filler, front-loaded with the resource identity before the use cases and the filter list. The example question phrasing is the most efficient way to convey intent.

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 10-parameter read tool with full schema coverage and no output schema, the description replaces the missing return documentation by enumerating the fields each prop contains. The one gap is sibling positioning — it never clarifies when to reach for prop_history or line_move instead.

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% and every parameter already carries a description, including defaults, enums and examples. The description's sentence listing filterable dimensions maps one-to-one onto the schema and adds ordering guidance but no new meaning, so the 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?

States a specific verb and resource ('Current FanDuel player prop lines and prices'), then anchors it with two literal example questions an agent would be asked, and enumerates the returned fields. It is immediately distinguishable from siblings like prop_history or line_move by its present-tense 'current' framing.

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 concrete use cases — answering 'what is the line for <player> <stat>?' and scanning a game or league board — and names the filter dimensions that support each. It stops short of explicit when-not guidance or naming alternative sibling tools such as prop_history or recent_changes for historical data.

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