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

Goes well beyond the readOnly/idempotent annotations: it discloses the published/playable filter, the 8-day verification window, that zero results is a success with code NO_MATCHES, and that up to 3 relaxations are returned whose args can be replayed. It also mandates quoting match_reasons, linking play_url, and rendering the attribution line.

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?

Purpose and scope are front-loaded, and nearly every clause carries operational information about filtering, empty results, or output handling. It is dense and parenthetical-heavy, and it inconsistently names the reason field first as similarity_reasons and later as match_reasons, which costs clarity.

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 13-parameter tool, it adequately covers the behavioral contract an agent needs: filtering guarantees, empty-result semantics, relaxation replay, and output/attribution rules, and an output schema exists so return shape needn't be spelled out. The unaddressed optional filters (mood, difficulty, session_length_max, min_quality) remain gaps.

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 only 15% across 13 parameters, so the description must compensate; it explains plays, include_listing_only, and the content_rating_max default, but leaves mood, genre, difficulty, inputs, players, min_quality, and session_length_max undefined beyond their names and enums.

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 opens with a precise verb+resource framing: games similar to an anchor game, ordered by similarity. This distinguishes it functionally from sibling search_games/trending without naming them, so it is clear but not explicitly differentiated.

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 gives concrete selection guidance for optional filters: when to use include_listing_only=true, that plays=here vs developer_site selects one kind, and that content_rating_max defaults to teen. It does not state when to prefer this tool over search_games or get_game, leaving that to inference.

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