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

Annotations already establish readOnly/idempotent/openWorld/destructive=false, so safety is covered. The description usefully adds behavior beyond them: what happens when neither team nor league is supplied, and the international-break fallback is captured in the schema. No contradictions; a genuinely useful default is disclosed.

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 verb+resource before examples. The example queries earn their place by clarifying intent, though they are illustrative rather than strictly necessary.

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 simple, zero-parameter-required read tool with fully documented schema and no output schema, the description covers purpose, usage triggers, and default behavior. The only mild gap is not distinguishing itself from get_results, but nothing needed to invoke it correctly is missing.

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%, so every parameter is already documented (days window and default, team, enumerated leagues, country kick-off behavior). The description only restates the team/league idea and adds no format or unit detail beyond the schema, so the baseline of 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) plus a scope (a club or a league), which cleanly separates it from siblings like get_results (past matches) and get_table (standings). The default-League behavior is stated up front so the agent knows what happens with no input.

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 natural-language trigger examples ('who do Liverpool play next?', 'what's on in La Liga this weekend?') and explicitly defines the no-argument fallback (Premier League). It never names the sibling it competes with (get_results for played matches), so routing is only implied rather than contrasted.

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