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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the bar is lower. The description adds genuinely useful behavior beyond that: no API key is required and the call does not consume API quota, which directly affects an agent's willingness to call it speculatively.

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?

One dense sentence that front-loads the primary content (sport codes and market keys) and appends the ancillary bookmaker list and cost note. Every clause carries information; the semicolon-chained structure is slightly heavy but nothing is wasted.

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 no output schema, the description carries the burden of describing returns, and it does so at a high level: sport codes, market keys per sport, and bookmaker id/name pairs. It omits the concrete response shape (grouping, ordering), but for a one-optional-param static reference tool this is close to sufficient.

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 single enum parameter is documented in the schema itself ('Only this sport's markets. Leave it off for every sport.'). The description does not mention the sport filter or how it interacts with the returned content, so it adds nothing 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?

The description states exactly what the tool returns: the sport codes accepted by get_odds and get_best_price with their market keys, the sports get_player_props accepts, and the bookmakers (id and name). It names its sibling tools and the relationship to each, so an agent can distinguish this discovery tool from the betting tools without opening a 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?

Usage is strongly implied by naming get_odds, get_best_price and get_player_props as consumers of these codes, and the 'needs no key and costs no API call' note makes it an obvious low-cost lookup. It stops short of explicitly saying 'call this first to discover valid values before invoking the odds tools,' which would make it a 5.

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