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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds real behavioral context beyond that: the default scope is the Premier League when no team or league is given, which an agent would otherwise have to guess.

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 purpose, then usage examples, then the default behavior. The leading 'Form Guide.' fragment merely restates the title and is the only wasted token.

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 four-parameter, zero-required read tool this is nearly complete: purpose, examples, default scope and the optional country/time behavior are all implied. The lack of an output schema means return shape is only loosely conveyed, but fixture listings are self-explanatory.

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% and the schema already documents days, team, league and country in more detail than the description (including the 404 on unknown leagues and the international-break fallback). The description's only parameter-relevant statement is the no-argument default, so 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?

States a specific verb and resource ('Upcoming fixtures') and clearly scopes it to a club or league, which distinguishes it from formguide_get_results, formguide_get_table and formguide_compare_teams without opening any 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?

Gives concrete usage contexts ('who do Liverpool play next?', 'what's on in La Liga this weekend?') and states the fallback when neither team nor league is supplied. It never explicitly excludes siblings such as get_results, but the intent is unambiguous.

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