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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so safety needs no restating. The description adds genuine value beyond them: it explains the substitution mechanics, that extra transfers cost 4 points, that no wildcards exist this season, and critically that badgie_rank is the Badgie ranking rather than an official one — a semantic caveat an agent would otherwise misinterpret. It does not mention behavior when no season is active or what an empty result looks like.

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?

It is front-loaded with the returned data, which is the right order, but the second half is a dense rules block that partly repeats earlier content (the 3 starters are described twice) and carries game lore (no wildcards) of marginal selection value. The entire description is also in Spanish while the tool name, title and sibling names are English, which adds a parsing burden and is not explained.

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 carries full responsibility for describing the return payload, and it does so thoroughly, component by component, plus the scoring rules needed to interpret points and captain multipliers. What is missing is minor: no statement about error or empty-season behavior, and the Spanish-only text is inconsistent with the rest of the tool surface.

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?

The input schema has zero properties, so there is nothing for the description to disambiguate and the baseline of 4 applies. The description correctly implies the call is parameterless and scoped to the authenticated player.

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 names the specific resource it returns and enumerates its components: the player's team, bench, points, rank, the week's tournament with 3 starters and a captain, ordered reserves, substitutions, remaining free transfer, and league memberships. That is far more concrete than the bare title. It stops short of naming how it differs from get_fantasy_field or get_fantasy_standings, so an agent must infer the boundary from the 'su equipo / sus ligas' framing.

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?

Usage is only implied: the possessive framing ('el equipo del jugador', 'sus ligas') signals a personal season overview rather than a field or standings query. There is no explicit 'use this when…' statement, no exclusion, and no pointer to suggest_fantasy_squad or suggest_fantasy_team for lineup decisions. The long rules passage supplies game context but not selection guidance.

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