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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds genuinely useful behavioral context beyond them: pagination is one month per page and the returned app IDs are not enriched with names, which changes how an agent must chain calls.

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?

Two sentences, front-loaded with the primary purpose before the resolution/alternative guidance. Every clause carries distinct information (paging, contents, enrichment caveat, alternatives) 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 return values need no prose. For a zero-parameter, read-only listing tool the description covers scope, paging, the enrichment gap, and ID resolution paths adequately; only an explicit note on historical depth or whether a specific month can be targeted 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?

Zero parameters, so the schema imposes no semantic burden and the baseline is 4. The description adds no parameter detail because there is nothing to describe, which is appropriate.

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 (Fetch) and resource (Steam's monthly top-releases index), then adds distinguishing detail: one month per page, returning the month and top-released app IDs, with names not enriched. An agent can tell this apart from steam_top_sellers and steam_charts_most_played without opening any schema.

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?

Names concrete alternatives for the downstream task (steam_app, datasets_steam_charts_search for stored snapshots, and comparison tools steam_top_sellers, steam_charts_most_played, steam_charts_concurrent). It clearly routes ID resolution and comparison, though it doesn't explicitly state when to prefer this tool over a stored-snapshot source for the index itself.

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