FanDuel native game markets

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and external-liveness profile is covered. The description adds genuinely useful non-obvious behavior: filters are case-sensitive and must match FanDuel's exact casing, and the API key must have the fanduel source enabled plus FanDuel chosen as a bookmaker. That prerequisite is real operational context beyond the annotations, though pagination and result shape remain undisclosed.

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?

Three short sentences, front-loaded with the resource and scope, with no filler. The dashboard prerequisite sentence is slightly compressed to the point of ambiguity ('The key needs the fanduel source'), 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?

For a two-parameter read-only list tool with no output schema, the definition covers purpose, the key/bookmaker prerequisite and casing behavior. It still leaves the agent unsure about what a market/selection record contains and how to page through results beyond limit, which matters for an open-world external feed.

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 0%, so the two parameters (limit, league) are only documented by their names, types, default and enum. The description adds that league scoping yields 'markets and selections by league' and that filtering is case-exact, which is meaningful for the enum values, but it says nothing about the limit semantics or defaults.

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 says 'FanDuel native markets and selections by league', which names a resource (markets/selections) and a scope (FanDuel native, by league), but the verb is implicit — it never says 'list' or 'fetch'. It does distinguish itself from generic odds siblings by specifying 'FanDuel native' and 'FanDuel exact case', so an agent can infer this is the FanDuel-specific market feed rather than a multi-book comparison.

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?

There is no explicit when-to-use or when-not-to-use guidance. The closest thing is the prerequisite note about needing the fanduel source and FanDuel selected as a bookmaker in the dashboard, which is a precondition rather than a routing rule. It never tells the agent to prefer get_odds_board or get_odds instead when multi-book data is wanted.

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