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

Annotations cover the safety profile (readOnly, idempotent, non-destructive), and the description layers on behavior they cannot express: no API key required, $0.003/call cost, data freshness/join semantics ('joined with our primary-source event pressure when covered'), and an explicit exclusion ('Liquidations are not included').

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 purpose and the data inventory are front-loaded in a single dense sentence, and the routing/alternatives follow. It is long and field-heavy, but the enumeration is justified because there is no output schema; only minor tightening is possible.

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 2-param read tool with no output schema, the description enumerates the returned fields (funding, OI, mark/oracle/mid, premium, volume, flags), notes the event-pressure join, and states what is excluded — everything an agent needs to decide and call it.

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 100%, so symbol and since are already fully documented in the schema, including case-insensitivity and the 24h default. The description adds only an example ticker list and the notion of hourly funding resolution, which is the expected baseline when the schema does the heavy lifting.

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+resource: perpetual-futures microstructure for ONE coin from Hyperliquid's public API. It explicitly distinguishes itself from price_for (price only) and carry_funding_matrix (every perp), so an agent can route without opening sibling schemas.

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?

Gives concrete trigger scenarios ('before sizing a perp position', 'detect crowded funding', 'market-structure leg next to events_since') and names two alternatives with the condition that selects each: price_for for price only, carry_funding_matrix for all perps.

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