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

Annotations already cover read-only/idempotent semantics, but the description adds genuinely new behavioral context: a $0.01 cost, x402 payment instructions in the response, source provenance, and explicit execution-risk warnings. The only shortfall is that it does not resolve whether a call returns actual rate data or just payment instructions, which leaves a meaningful call-outcome ambiguity.

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 response content is front-loaded in the first sentence, with cost/payment information second, which reflects the right priority order. The feature list is dense and slightly catalog-like, but every clause carries information and there is no filler.

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, the description does the work of describing return content (rates, intervals, annualized figures, spread signals, provenance, risk warnings), which is substantial. The remaining gap is the paid-endpoint mechanics: an agent cannot tell from the definition whether a successful call yields usable data or a payment handshake.

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 description coverage is 0%, so the description carries the full burden. It hints at two of the three parameters indirectly — 'open interest filters' maps to minOiUsd and 'spread/arbitrage signals'/'annualized comparisons' map to the spread/apr sort enum — but it never names them or explains defaults, and the limit parameter has no coverage anywhere.

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 specific resource (perpetual-futures funding rates) and enumerates the covered venues (Hyperliquid, Binance, Bybit), plus the derived content it returns: venue intervals, annualized comparisons, spread/arbitrage signals. No sibling tool in the list deals with funding rates, so an agent can immediately distinguish it from get_price_history, get_stock_quote, or get_token_snapshot.

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?

Usage is only implied: the mention of open-interest filters and spread/arbitrage signals suggests it is the tool for cross-venue funding comparison, but there is no explicit when-to-use statement, no when-not guidance, and no named alternative among the 39 siblings. An agent must infer the trigger conditions from the feature list.

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