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

Annotations already cover read-only, non-destructive and closed-world, so the description's job is added context — and it delivers: finished seasons only, the since-2010/11 (or league's first recorded season) cutoff, ranking basis (league results), and the no-cross-league-comparison invariant. It doesn't cover what happens if both club and scope are supplied, which would be the remaining behavioral unknown.

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?

Return fields are front-loaded, which is good, but the two operating modes and their differing count limits are packed into one long semicolon-joined sentence with stacked parentheticals. Nothing is wasted, yet the mode split would scan far better as two separate statements.

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 and 0% parameter coverage, the description does the heavy lifting by listing returned fields and both modes. Still missing: the parameter-name mapping for the league slug, behavior when both 'club' and 'scope' are passed, and whether results are ordered by score or rank.

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 0%, so the description must carry all parameter meaning. It does explain counts and defaults (1–20, default 10 for leagues; 1–10 for clubs) and that slugs come from resolve, but it never names the 'scope' parameter — an agent must infer that the league slug goes into 'scope' rather than 'club'. That implicit mapping is the key gap at zero schema coverage.

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?

The description states a specific verb and resource (returns club-seasons ranked within one league) and enumerates the return fields: score, league rank, longest unbeaten run, club page URL. It also names its two modes (league-wide vs. one club's best seasons), which separates it from generic siblings like rankings or league_runs, though it never explicitly contrasts itself with those siblings.

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?

It gives clear operating conditions: finished seasons only, never compares sides across leagues, league slug comes 'from resolve' (an implied prerequisite call to a named sibling), and count bounds differ per mode. It stops short of explicit when-not-to-use-this-tool guidance or naming a substitute tool for adjacent questions.

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