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

With no annotations present, the description carries the full burden and does substantial work: it explains that marketplace days are medians with min/p75/offer count while list-price days carry posted prices, that each row identifies its kind, and that the two must never be blended. It omits operational traits an agent might want — pagination, row volume, permissions, error behaviour for unknown GPU slugs.

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 tight sentences with no filler, and the core scope statement leads. The marketplace-vs-list-price rule is dense but earns its place as the fact most likely to be misused; only the 'never forecasts' clause is marginally redundant with 'price history'.

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 3-param read tool with no annotations and no output schema, the description covers semantics well and the schema covers parameter shapes. It leaves the agent without return-shape guidance (row fields beyond the median/p75 mention), ordering, and the resolution of the 90-vs-365-day conflict — gaps an agent would hit on first call.

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 the schema already explains gpu, days and source, giving a baseline of 3. The description arguably undercuts this by stating 'up to 90 days' while the days parameter allows a maximum of 365 — a conflict that could cause an agent to reject valid requests or mis-set the window. Because the description's only parameter-relevant claim is the one that contradicts the schema, it adds risk rather than meaning.

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+resource combination — daily price history per GPU class and source — plus its scope (up to 90 days) and its role in feeding the Rent Index. It is clearly distinguishable from list/trend tools in substance, but never names the sibling it replaces, so an agent must infer that gpu_prices (not this) is the current-price tool.

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?

The description implies the use case (historical series underlying the Rent Index and 30-day range) and states one boundary — it never forecasts. However, it gives no explicit when-to-use/when-not guidance and never routes the agent to gpu_prices, find_fit or the other siblings, leaving tool selection to inference.

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