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

Annotations already declare readOnly, idempotent, non-destructive, openWorld, so the safety profile is covered. The description adds genuine behavior beyond that: the return format (Markdown), the per-field as-of dating convention, and a real availability constraint (adult-only titles excluded). No auth or rate-limit notes, but the added context is substantive.

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 front-loaded sentence with the identity and identifier source first, followed by the payload enumeration and the adult-titles caveat. The return-field enumeration is long, and since an output schema exists it is partly redundant, costing a point on leanness.

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 rich annotations, an output schema, and a fully documented single parameter, the description only needs to add identity, sourcing, scope and constraints — all of which it does. Nothing required for correct invocation is missing.

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% and the single 'id' parameter is already documented in the schema with the same app-id/slug example. The description repeats that meaning rather than extending it, so the 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 a specific verb ('Read') and resource ('one Steam game's record from steamcozy.com') and pins the identifier source ('id from search/find_games ... or its slug'). An agent can distinguish it from find_games, search and new_games purely from this sentence.

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 routes the agent: the id comes from search/find_games, and it states the exclusion that adult-only titles are unavailable. It stops short of naming an alternative tool for those blocked cases or stating when to prefer search over fetch, so it is strong routing rather than full when/when-not guidance.

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