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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new context: it is free of charge and it reads from public URLs, which the annotations do not convey.

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: cost, contents, and use case. The cost fact is front-loaded and every sentence carries information with no padding.

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 not be explained, yet the description still summarizes the payload usefully. Combined with the free-cost note, the timing advice, and the annotation-backed safety profile, an agent has what it needs; only explicit routing to sibling freshness/snapshot tools is absent.

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?

The tool takes no parameters, so the baseline is 4. The description does not need to add param meaning, and it correctly adds none.

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 specific resource (freshness of every data source) and enumerates the returned fields per source: last successful snapshot/event, staleness in days, and public URL. This distinguishes it from per-source siblings like spot_latest or gpu_snapshot by covering all sources, though it never names an alternative explicitly.

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?

"Use it to decide whether a fixing or quote is current before paying for it" gives a concrete precondition for invocation. It stops short of naming alternatives (e.g., when to prefer attestations or a specific snapshot tool), so it is clear context without exclusions.

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