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

With no annotations, the description carries the full burden; it does disclose useful traits: funding is paid hourly, it is the main holding cost, and it lists the summary components (current rate, mean, annualized mean, min/max, share of positive periods, direction of drift). However, it doesn't reveal how the history is structured, what the response looks like, or how ambiguous parameters (coin vs symbol) are handled.

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 two sentences: the first front-loads the purpose and summary fields, the second adds decision-relevant context. There is no filler, and every clause earns its place.

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?

For a read-only data tool with no annotations and no output schema, the description is reasonably complete on the return summary but thin on invocation details: which parameter identifies the perpetual, what hours vs limit mean, and defaults for the optional parameters. An agent would still have to guess at important call semantics.

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 baseline is 3. The description adds only that the tool is for 'one perpetual,' which hints at the coin/symbol parameter intent, but it doesn't explain the hours/limit semantics or the relationship between coin and symbol beyond what the schema already says.

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 clearly states the resource: Hyperliquid funding-rate history for a single perpetual, plus the carry-trade summary fields it returns. It is specific enough to be distinguished from sibling tools like x402-hyperliquid-predicted-funding and x402-hyperliquid-candles, though it lacks an explicit verb and doesn't name any sibling.

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 gives concrete usage context: funding is paid hourly and is the main cost of holding a perp, so the result determines whether a position is worth keeping. This tells an agent when reaching for this tool makes sense, but it doesn't explicitly contrast it with alternatives like predicted funding or other Hyperliquid data tools.

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