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

Annotations only cover read-only and open-world; the description adds substantive behavior: unknown choices come back as failures rather than silently dropped, only single bets (not combinations) are priced, and a 1-25 choice-id ceiling applies. These are exactly the failure modes an agent needs before calling.

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 dense sentences, front-loaded with what is returned and followed by usage and constraints. Nothing is wasted, though the second sentence packs several clauses (source, cardinality, exclusion, auth) that could read more cleanly.

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 an output schema handling return shape and annotations covering safety, the description supplies all that remains: input provenance, cardinality limits, failure semantics, and the parlay/auth limitation. An agent can call this correctly without further inference.

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 the schema already explains ramp_event_id ("not its event_id") and the 1-25 choice_id list, so the description largely restates structured data. It adds only marginal framing by tying choice ids to the builder response, so the baseline 3 is right.

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 (get live single-bet odds for FanDuel bet-builder choices) and scopes the output formats (decimal, American, fractional). It is clearly distinguishable from the sibling fanduel_sportsbook_builder, which it names as the source of inputs.

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 says when to use it ("Use it to price what fanduel_sportsbook_builder offers") and names the alternative flow implicitly by pointing at the builder response. It also sets an exclusion boundary: combinations of choices cannot be priced here and require an account.

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