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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), yet the description adds real behavior the annotations cannot: resolution degrades by span (half-hour to 2 days, hourly to 14 days, daily beyond), and retention is tier-gated (Free/Plus 7 days, Pro/Studio since Sep 27 2026). It also discloses the returned dataset shape. Missing only things like row limits or rate 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?

Front-loaded with purpose and line types, then resolution and retention — a sensible order for a 7-parameter tool. It is dense but mostly earns its length; the closing line 'Each game counts toward the day's games' history' is opaque and arguably wasted.

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 no output schema, the description compensates by describing the return dataset (a t or d time column plus one column per line) and by documenting resolution tiers, retention limits, line cap, and tier entitlements. An agent has enough to call it and interpret results without further context.

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%, so baseline is 3, but the description adds meaning beyond the schema: it explains that the four list parameters correspond to line types and that the lookback span drives output resolution, plus the 'd column of days' format. This goes past restating field text, though it never ties semantics to specific parameter 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 concrete resource — player counts over time as a multi-line series — and enumerates the four line types (games, all of Roblox, genre's games, trend word's games), so an agent can tell what it returns. It gestures at a sibling relationship ('the way RoTerminal's charts read them') but never explicitly positions itself against charts, compare, or days.

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 through constraints (up to 8 lines, span-dependent resolution, tier-based lookback) rather than stated as when-to-use versus alternatives. There is no sentence telling the agent to choose this over `compare` for multi-game history or `days` for single-day detail, so routing must be inferred.

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