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

Annotations already cover readOnly/idempotent/destructive, so the description's real value-add is the $0.001/call price disclosure and the response shape (candles[] and summary fields). It does not state default interval/limit behavior or pagination/truncation at the 500 cap, which is the remaining gap.

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?

Three compact sentences: output shape, cost, usage routing. Every clause earns its place and the routing constraint is front-loaded.

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 simple read-only 3-param tool with no output schema, the description sketches return values and cost well. Missing defaults for interval/limit and any hint about candle ordering or partial data at range edges keeps it short of complete.

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 only 33% – only 'coin' is documented (with an example). The description does not explain what 'limit' means (max 500, default?), nor clarify interval semantics beyond the enum's self-evident values. With low coverage, the description should compensate and does not.

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 the specific verb+resource (OHLCV candles for one Hyperliquid perp, main or HIP-3) and even enumerates the return fields. An agent can distinguish it from the many carry_, oracle_, and polymarket_ siblings without opening the schema.

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?

Explicitly scopes usage: 'Use for price history (OHLCV) of one Hyperliquid perp; for price now use price_for.' It names the alternative and the condition that selects it, leaving nothing to inference.

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