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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds genuine behavioral context beyond that: cups are assembled round by round, each match carries a `round`, and the response lists `rounds` with their ids — useful for an agent handling knockout competitions.

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?

Front-loaded and efficient: capability first, then the cup/round nuance, then alternatives. The matchday guidance is stated twice in slightly different wording (second and third sentences), which is minor redundancy rather than bloat.

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?

With an output schema present and full parameter documentation in the schema, the description only needs to supply scope, filtering behavior, cup-structure nuance and sibling routing — and it does all four. Nothing an agent needs to invoke this 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 all four parameters (competition_id, team_id, date_from, date_to) are already documented. The description only restates that filtering by team and date window is optional, adding no format or constraint detail beyond the schema; 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 with scope: 'Returns every match of a competition's season (fixtures and results), optionally filtered to one team and a date window.' It also explains the round-based structure of cup competitions, so the returned shape of the data is clear without opening the 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?

Explicitly names when to use it ('for a complete schedule') and routes to alternatives by name: fussballde_matchday for a single matchday, fussballde_team_matches for one team across competitions. The only flaw is a hyphen/underscore inconsistency ('fussballde-matchday' vs 'fussballde_matchday'), which is cosmetic and doesn't obscure the reference.

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