List leagues

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

Annotations already establish readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful context beyond them: the tool is plan-gated and the free Developer plan only covers MLB, NFL, AFL and NRL, which matters for interpreting results. It says nothing about pagination or ordering, which is a minor gap for a small enumeration.

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 sentences, front-loaded with the core purpose and free of filler; the plan-coverage detail earns its place as gating information. The trailing 'leagueID' reference slightly muddies the message since leagueID is not a parameter of this tool.

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 one-optional-parameter enumeration tool with no output schema, the description covers purpose, usage trigger, and the plan-access behavior an agent needs to interpret results. Only return-shape details (fields, ordering) are omitted, which is acceptable given no output schema exists.

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 100% for the single optional sport_id parameter, including an example value, so baseline is 3. The description mentions 'leagueID' but does not clarify sport_id's filtering semantics beyond what the schema already documents.

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 a specific verb and resource ('List the leagues SockOdds carries') and adds what the response conveys (plan read-access per league). It is clearly distinct from odds-oriented siblings like get_odds and best_price, though it never names a sibling explicitly.

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?

It gives a clear triggering condition: 'Use it when you are unsure of a leagueID.' That tells the agent when this tool is the right entry point, though it does not state when not to use it or name an alternative lookup path.

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