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 meaningful scope beyond that: the data is all-time and spans 'across all sessions', i.e. a cross-session aggregate rather than a single-session view — a real behavioral distinction that shapes how results are interpreted.

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 sentences, zero filler, and the scope ('all-time ... for the user's team') is front-loaded before the usage hint. Nothing redundant with the title 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?

An output schema exists, so return-format detail is not required, and the description already previews the key fields. With one optional param, no required inputs and full annotation coverage, an agent has everything needed to invoke this 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 description coverage is 100% and the single 'limit' param is fully documented (range 1–100, default 20) in the schema itself. The description says nothing beyond the schema about the param, so the 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 ('Get the all-time Fun Friday leaderboard for the user's team') and enumerates what is returned (total score, games played, rank). The resource is unique among its siblings (create_pack, create_session, get_session, get_team, list_games, list_sessions), so an agent can distinguish it immediately.

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?

Provides concrete usage context with example intents ('who is top of the leaderboard?', 'write up a standings summary'). However, it names no alternatives or when-not conditions, so routing versus e.g. funfriday_get_team or funfriday_list_sessions is left to inference.

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