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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds scope context that annotations cannot convey: this returns a fixed set of five leagues that gate access to fixtures and team data. It does not describe the shape of the returned entries, which is a minor gap for a zero-parameter list.

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 short sentences, the primary purpose front-loaded followed by the routing hint. No redundant restatement of the tool name or annotations.

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 zero-parameter catalog tool with no output schema, the description is nearly complete: it tells the agent what the list contains and where to go for match history. Only the fields available per league are left unspecified, which the agent can discover at call time.

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?

The tool takes no parameters, so the baseline is 4; there is nothing in the schema needing explanation and the description does not add spurious parameter guidance.

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: list the five major football leagues, and qualifies them as the ones that support fixtures and team catalogs. It is distinguishable from siblings such as get_fixtures or search_teams since it is the entry point catalog, though it does not name those siblings directly.

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?

Gives clear usage context (use this to find leagues that have fixture and team-catalog coverage) and an explicit exclusion: for historical scores, query by competition or team keyword instead. The alternative tool is not named, so the agent must infer it from siblings.

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