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

Annotations already declare readOnlyHint=true and openWorldHint=true, and the description adds genuinely new behavior: the prerequisite slug source and that an unknown slug yields an error rather than an empty result. It does not mention the region/lobby dimension, but for a read-only lookup this is solid added context.

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, no filler. The field enumeration is front-loaded and the usage/prerequisite note follows, so the most decision-relevant content comes first.

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 still previews them. Combined with annotations and a fully documented schema, this is essentially complete; only the region/lobby choice is 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 coverage is 100%, so the schema already documents both 'game' and 'region'. The description restates the slug provenance (already in the schema description) and says nothing about the mi/on region parameter, so it adds little beyond the structured fields.

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 ('Get') and resource ('FanDuel Casino game's details') and enumerates the returned fields (category, bet range, studio, volatility, themes, features, live player count, badge, play-link identifiers). This is clearly distinguishable from the sibling category/listing tools.

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?

'Use it to read one game' scopes it against the browsing siblings, and it names the required input source ('a game slug from fanduel_casino_category') plus the failure mode ('an unknown game returns an error'). It stops short of explicitly naming the alternative to call for listing/browsing, but the scoping is clear.

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