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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds genuinely non-obvious behavior: data is sampled every 10 minutes (so it may lag live truth) and the gta6 category does not exist before the unlock date. It says nothing about volume limits, ordering of 'biggest streams', or error/empty behavior.

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 short sentences, front-loaded with what the tool returns, then the freshness/scope constraint, then the critical caveat. No filler and nothing repeated from the schema beyond the enum values themselves.

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 single-parameter, read-only snapshot tool with no output schema, the description covers scope, freshness, and the major edge case (gta6 unavailable pre-unlock). It stops short of describing what a returned 'biggest stream' entry looks like or whether results can be empty for low-traffic games.

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 enum parameter is documented with its default, so the baseline is 3. The description earns an extra point by explaining that 'gta6' silently has no underlying category until 19 Nov 2026, which is meaning the schema does not convey.

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 names a specific verb+resource combination: live Twitch viewers and live stream counts for GTA 6 or GTA 5, plus the biggest current streams. That is clearly distinguishable from analytics-oriented siblings like get_trend_radar or get_best_time_to_stream, though those siblings are never named as contrasts.

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 frames the tool as a real-time snapshot ('now', sampled every 10 minutes) and explicitly redirects hour-by-hour analysis to Studio Pro, which is a usable when-not signal. It also warns that GTA 6 has no Twitch category until 19 Nov 2026, which tells the agent when the gta6 option is pointless — but it never names a sibling tool as the alternative.

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