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

Annotations already cover readOnlyHint and openWorldHint, so safety is declared. The description adds the valuable edge case that an empty event list is valid when nothing is scheduled, plus the market types returned. It stops short of describing auth needs or rate limits, but the output schema carries return-shape detail.

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 tight sentences with zero filler; the primary purpose and scope are front-loaded, and the routing guidance follows compactly. 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?

Complete for a read-only, single-param market fetch: the purpose, the empty-result caveat, and the alternative tool routing are all present, and return-value structure is handled by the existing output 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?

One parameter with 100% schema description coverage, so baseline is 3. The description's 'numeric league_id' only echoes the schema's 'Numeric DraftKings league id' without adding format, source, or lookup guidance.

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 (upcoming-event DraftKings moneyline, spread, and total markets) scoped by league_id. It clearly distinguishes itself from sibling odds-related tools by naming the market types it returns.

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?

Explicitly routes to alternatives: draftkings_league_events to browse events, draftkings_event_markets for one event, draftkings_live for in-progress, and draftkings_futures for futures. Names both the alternatives and the conditions that select them.

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