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

Annotations already declare this as a safe, read-only, idempotent, open-world operation, so the description does not need to re-cover destruction or mutation risk. It adds useful behavioral context by enumerating the returned field groups (summary, release dates, genres, ratings, DLC, etc.), which helps an agent decide whether this tool returns the detail it needs.

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?

The description is front-loaded with the core purpose, then lists return fields compactly, and closes with usage guidance and a concrete example. The field inventory is somewhat long but earns its place by helping the agent gauge coverage without an output schema.

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?

For a read-only detail tool with rich annotations, no output schema, and full input schema coverage, the description provides enough: it names the source, input forms, return contents, and placement in the search-then-fetch flow. It omits only minor operational details like error behavior on a missing id/slug, which are not strictly necessary to call it 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%, so the schema already documents id, slug, and _apiKey. The description reinforces 'by numeric id or slug' and provides an example, but adds no syntax, format, or constraint details beyond what the schema already states.

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 resource ('one video game in full from IGDB') and the two acceptable input forms (numeric id or slug), then enumerates the returned data categories. It distinguishes itself from igdb_search_games by saying 'in full' and 'Use after igdb_search_games,' and from igdb_companies/igdb_platforms by scoping the resource to a single game.

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?

Explicitly instructs the agent to use it after igdb_search_games, giving a clear sequence and input expectation. It does not state when not to use it or compare directly with sibling IGDB detail tools for companies/platforms, so it falls short of a full 5.

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