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

Annotations already cover the read-only/idempotent safety profile, and the description goes well beyond them: alias resolution with requested_id set, the fact that listing-only, stale or suspect games are returned, the play_ready gate on play_url, and two named error conditions (NOT_FOUND, GONE) with their meanings. That is exactly the extra behavioral context annotations cannot carry.

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?

Three tight sentences, front-loaded with what is returned, then the presentation caveat, then error semantics. Every clause carries operational information (identifier formats, requested_id, play_ready gate, error codes) with no filler.

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 the description correctly avoids enumerating return fields and instead covers what schema cannot: alias resolution behavior, degraded-data caveats, and error semantics. For a one-parameter read tool this is complete.

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 100% and the single parameter's description already states the 6-char/slug-id format and alias resolution. The description's "by id or {slug}-{id}" largely restates that, so baseline 3 applies — it neither compensates for a gap nor adds new syntax detail.

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?

"Full details of one game" gives a specific verb+resource, and the accepted identifier forms (6-char id or {slug}-{id}) scope it precisely. It is immediately distinguishable from search_games, games_like, trending and random_game, which return collections or selections rather than a single addressed record.

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 establishes the use case (fetch one known game, including aliased ids) and adds a concrete downstream rule: do NOT present play_url as playable unless play_ready is true. It does not explicitly route the agent to a sibling when the id is unknown or name-only, so the when-not path is implied by the NOT_FOUND error rather than stated.

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