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

The annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered structurally. The description's own contribution is the disclosure that constituents are returned so the value can be recomputed — useful, since there is no output schema — but it says nothing about how the days window changes what is returned or about result size/pagination when listing all series.

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, no filler, with the return contents stated before the list-all variant. The first sentence is long and front-loads examples ahead of the core behavior, but nothing is 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 carries the burden of describing returns and does so (latest value, constituent count, constituents). Both parameters are covered by the schema, leaving only minor gaps around how the look-back window affects the returned value.

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 100%, so the schema already documents both parameters, making 3 the baseline. The example slugs (eu-vps-2vcpu-4gb-floor, frontier-token-input-floor) do add domain meaning about slug format, but the description says nothing about the days window or its interaction with the series value.

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 resource (a named daily index series) plus exactly what comes back — latest value, constituent count, and constituents — so an agent knows this returns data it can verify. It never names a sibling (get_price, get_history), so the boundary against those tools has to be inferred from domain knowledge.

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?

"Omit series to list all series with their latest values" explicitly documents the two call modes and the condition that selects each. It gives clear usage context but no exclusions or routing advice versus get_history/get_price, so it stops short of a 5.

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