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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuine behavioral value by noting that an empty market list is valid when none are posted, which prevents the agent from misreading no results as an error. It stops short of describing pagination or auth needs.

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?

Two sentences, zero waste. The primary action and its scope are front-loaded, and the sibling routing follows immediately after. Every clause earns its place.

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?

An output schema exists, so return values need not be explained, and the description covers the key edge case (empty list is valid). For a read-only two-parameter lookup this is nearly complete; a hint on where league_id/subcategory_id come from (e.g. draftkings_leagues) would close the remaining gap.

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%, so both parameters are already documented as numeric DraftKings ids. The description merely restates that they are numeric and required, adding no syntax, format, or lookup-hierarchy detail 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?

States a specific verb (Fetch) and resource (DraftKings league-level futures market records and selections), and explicitly names the two siblings it is not, so the agent can distinguish it from draftkings_event_markets and draftkings_odds without opening any 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?

Provides explicit routing: use draftkings_event_markets for event-level markets or draftkings_odds for upcoming-event odds. The condition that selects this tool (league-level futures) versus its alternatives is unambiguous.

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