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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful non-annotation context: it is 'Free' and the output carries a sellability verdict. It stops short of defining the freshness threshold or the exact return shape.

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 tight sentences with pricing front-loaded ('Free.') and no filler. The fragment style is efficient, though it is brief enough that some behavioral detail could have been added without bloat.

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 partially compensates by naming what is returned (last refresh time and a freshness verdict). For a simple zero-parameter status tool this is close to sufficient, though the freshness criterion itself is left undefined.

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 and schema coverage is 100%, so there is nothing for the description to disambiguate. Baseline 4 applies for a no-parameter tool.

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 ('Shows') and resource ('Hyperliquid feed was last refreshed') plus the freshness verdict, so an agent can tell this is a status/freshness probe rather than a data-retrieval tool. It does not explicitly name sibling alternatives, but the purpose is unambiguous.

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 phrase 'fresh enough to be sold' implies the use case (validate freshness before selling/using the feed), which is a reasonable contextual cue. However, there is no explicit when-to-use statement or comparison to siblings like hyperliquid_market_brief, so guidance remains implied.

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