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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds one genuinely new behavioral fact — that it uses no live data — but says nothing about determinism, units of the returned figures, or how the 'funding-halved' case is derived.

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?

A single front-loaded sentence that leads with the outputs and then the required input shape; there is no filler. The curly-brace shorthand is dense but legible for an agent, though it borders on terse.

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?

With no output schema and a nearly empty legs schema, the description must carry the return-value burden. It lists the four computed metrics by name but never defines them (annualization basis, units, sign conventions) and leaves two numeric parameters unmentioned, so it is adequate rather than 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 40% and the legs array items are declared as a bare object with no properties at all, so the description's inline leg shape ({side, rate_pct per period, interval_hours, taker_bps, first_in_hours?}) carries the critical semantics that the schema omits entirely. It earns credit above the baseline for rescuing the most important undocumented structure, though leverage and slippage_bps remain unexplained.

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 the exact outputs it computes (net, net APR, breakeven, funding-halved case) and the resource (two manually typed-in legs), which clearly separates it from live-data siblings like funding_rates or best_opportunities. It stops short of a crisp verb+resource phrasing but the scope is unmistakable.

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?

The parenthetical '(no live data)' implies this is the tool for hypotheticals you type in rather than market lookups, which is a real usage cue. However, it never names an alternative tool or states an explicit when-not condition; the routing is left to inference from the sibling names.

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