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

Annotations already declare readOnly, idempotent, and closed-world behavior, so the description does not need to repeat the safety profile. It adds the return keys (snapshot_at, source, fields_kept, fields_dropped) as an example object, which is valuable because there is no output schema. It stops short of explaining how the snapshot is chosen or refreshed.

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?

The description is short and front-loaded: the content claim comes first, the typical user question second, and the return example last. Every sentence contributes. The 'What to cite:' fragment is a little informal, but that is minor.

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 and no parameters, the description carries the burden of describing the return shape, and it does so with an inline example. It is missing only freshness or refresh semantics, such as how often the snapshot changes or whether it can lag behind live counts.

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?

There are no parameters, so the baseline is 4. The description explicitly says 'No arguments,' which reinforces what the empty schema already shows. There is no further parameter meaning to add.

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 specific content: the snapshot date and source behind the other tools, plus which fields are kept or dropped. This clearly separates it from the sibling data tools, which return counts and totals rather than provenance. A slightly stronger verb framing than 'What to cite' would push it to a 5.

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 names the concrete question the tool answers ('Which day do these numbers describe and where do they come from?'), which tells an agent exactly when to call it. No explicit when-not or alternative is given, but for a zero-argument metadata tool with no comparable sibling, the implicit comparison is sufficient.

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