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

Despite annotations already marking the tool read-only and idempotent, the description adds substantial behavioral context: trending_basis indicates play-data vs recency fallback, results are limited to published/playable games verified within 8 days, listing-only handling is explained, and zero results returns NO_MATCHES with up to 3 executed relaxations. It also discloses output-handling requirements including quoting match_reasons, linking play_url, and rendering the attribution.

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 dense but front-loaded with the core purpose, then packs only relevant behavioral details into a short block. Every sentence contributes something material to selecting or invoking the tool correctly.

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 complex 13-parameter tool with an output schema, the description covers the most important behavioral and return-related semantics: fallback basis, verification window, zero-result behavior, relaxation retries, and attribution requirements. It is not fully complete because several filtering parameters remain undocumented, but the output schema reduces the burden to explain return values.

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 8% across 13 parameters. The description meaningfully explains plays, include_listing_only, content_rating_max, genre scope, and window, but leaves many filters such as mood, inputs, players, difficulty, min_quality, exclude_genres, session_length_max, and limit unelaborated beyond their enum names.

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 states a specific resource and scope: games trending over the last day or week, with genre scope when genre is set. This clearly distinguishes it from siblings such as new_games, random_game, and search_games without needing to name them.

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?

Usage is implied by the 'trending' framing and by details such as plays=here vs plays=developer_site and include_listing_only=true, but it never explicitly says when to choose this tool over new_games or search_games. The zero-results retry guidance is useful but is post-result behavior rather than pre-call usage guidance.

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