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

Annotations already cover safety (readOnlyHint=true, openWorldHint=false), and the description adds genuinely new behavioral detail: content is derived from provider data only, must be quoted as facts with no added predictions, null is a normal empty result with concrete causes, and non-English output is gated by the Insights feature. That is more than the annotations convey.

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 with the core purpose and packs return fields, null behavior and language caveats into one dense paragraph with no filler. It reads as slightly run-on with many parenthetical clauses, but every clause carries information.

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 no output schema, the description fully carries the return burden: it enumerates paragraphs, key_facts, what_it_means, summary_lang and summary_as_of, and explains when summary is null. For a read-only retrieval tool this is complete enough to call and interpret correctly.

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 coverage is 100%, so baseline is 3, but the description adds real meaning: id accepts a code or number, the summary_lang/summary_as_of fields are named as outputs, and critically the lang values de/es/it/fr only yield a team or league summary — an important constraint not visible in the schema. That extra semantics pushes it above baseline.

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+resource: a ready-made summary (paragraphs) for a match, team, league or player, built from the provider's own data (table places, form, meetings, season). An agent can tell this is a pre-written narrative product rather than raw stats. It does not, however, explicitly differentiate itself from close siblings like get_match_briefing, get_team_briefing, get_facts or get_league_facts, which sound very similar.

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 useful situational context: key_facts appear before kick-off, what_it_means after the result, and summary is null when there is nothing (match in play, stale page, under-18 player). It also notes the non-English path requires the Insights feature and that only the sport is needed in the plan. But it never names an alternative tool or says when to prefer this over the briefing/facts siblings, leaving the routing decision to inference.

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