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

Annotations already declare read-only/idempotent semantics, but the description adds ordering (best first), return tuple shape, unit conventions (USD per coin, sizes in base coin), and an auth-related constraint (venue without an account: hyperliquid only). These are exactly the traits an agent needs that annotations can't express.

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 tight sentences: purpose first, exclusion second, inputs/units/next-step last. No filler and nothing buried.

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?

Output schema exists, so return-value documentation is optional; the description still covers ordering and units, plus the auth constraint and sibling routing. Nothing an agent needs to call it correctly is missing.

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 the baseline is 3; the description goes further by disclosing the unauthenticated venue restriction and clarifying what price and size mean, though depth's 1-50 range merely repeats the schema bounds.

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 (order book levels for one perp contract on one exchange) and immediately differentiates from the closest sibling compare_perp_quotes_across_venues. An agent can distinguish it 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?

Gives an explicit use case ('judge liquidity before a large market order'), an explicit exclusion with a named alternative ('Not for the best price across exchanges'), and a next-step routing ('Next: preview_perp_order').

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