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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds a useful temporal scope signal ('today's' figures, i.e. a live snapshot rather than history), but says nothing about freshness cadence, caching, or what a consumer receives. That is additive but thin against the lower bar set by annotations.

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?

A single front-loaded sentence that leads with the owner and the temporal qualifier, then lists the payload items; nothing is padding. The dense jargon makes it terse to the point of opacity, but no sentence 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 parameters, no output schema, and annotations covering safety, the description's remaining job is to say what comes back — and it does, naming four distinct data categories. It is only short of a 5 because it never clarifies what 'line from Tack' or 'day of the experiment' actually mean, leaving the response shape partly guesswork.

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 zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. No misleading parameter language is present.

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 names a specific resource (today's real numbers) and enumerates its parts: money in, money out, experiment day, and today's line from Tack. That is far more than a restatement of the name. It loses a point because domain jargon ('Brasspage', 'Tack', 'the day of the experiment') is unexplained and siblings (check_site, pin_tack) are never referenced to sharpen the boundary.

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?

Only the word 'today' implies when this is appropriate; there is no explicit when-to-use, when-not-to-use, or comparison to check_site or pin_tack. An agent must infer entirely from the resource nouns whether this is the right tool.

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