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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds what the response centers on (Metascore and user score), but says nothing about where the slug comes from, whether the lookup fails on unknown slugs, or how fresh the scores are. Modest added value over the annotations.

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?

A single compact sentence with the key content front-loaded and zero filler. It is terse to the point of being minimal, but nothing is wasted.

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 values need not be described, and the annotations carry the safety profile. For a one-param detail lookup this is nearly sufficient, but the missing link to how an agent obtains a valid slug (browse/search) leaves a real workflow gap.

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?

Only one parameter, and schema coverage is 100% with the slug format examples ('elden-ring, oppenheimer, breaking-bad') already given in the schema. The description adds nothing about the slug, so 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 the resource precisely ('Metacritic game detail') and names the payload ('Metascore + user score'), which separates it from the movie/TV siblings and from metacritic_game_critic_reviews / metacritic_game_user_reviews, which cover reviews rather than the summary score. It does not explicitly name those siblings, so it falls short of a 5.

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?

No when-to-use statement, no prerequisites, and no alternatives named. An agent must infer from the name alone that this is the detail lookup to use after metacritic_browse or a search, and that the sibling review tools serve a different need.

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