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

With no annotations, the description carries the full burden and does real work: it discloses the return payload (candles plus change %, high/low, volume, annualized realized volatility), the 400-not-charged failure mode for unknown coins, and the per-call price of $0.002 USDC via x402. It omits rate limits, pagination beyond the 500-candle cap, and whether payment is settled per request, which keeps this at adequate rather than strong.

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?

It is dense but front-loaded: trigger first, then Input, Output, error behavior, example, and price. Every clause conveys usable information and there is no filler prose.

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 priced, unannotated data-fetch tool with no output schema, the description supplies the trigger, input semantics, return shape, error handling, and cost. The one real gap is pagination guidance for histories longer than 500 candles, which an agent would need to know.

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 coverage is already 100%, so the baseline is 3, but the description adds meaning the schema lacks: the interval enum values (1m-1M) are not enumerated in the schema, and it states that start/end accept ISO dates or unix timestamps and that start defaults to end minus limit times interval. The redundant limit range and defaults are harmless restatement.

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 concrete verb and resource ('price history' / 'OHLCV candles') and scopes it to Hyperliquid perps and HIP-3 markets with an example (xyz:TSLA). That is enough to separate it from hl_orderbook or hl_perp_metrics, though no sibling is named explicitly the way a 5 would require.

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 opens with an explicit trigger ('Use when an agent needs price history for...') and gives a concrete example call. There is no when-not guidance or named alternative for overlapping needs such as funding history or market snapshots, so it stops short of a 5.

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