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

With no annotations, the description carries the full burden and does well: it discloses the paid cost ($0.05 USDC / 50000 atomic), that no API keys are required, and that fundingRatePrediction and relativeFundingRate come from historical data. It omits rate limits, latency, and failure behavior, which keeps it short of a 5.

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 cost/payment fact is front-loaded, followed by source, return fields, and auth/parameter notes in a dense but well-ordered block. Every clause carries information, though the returned-field list is somewhat long for text that an output schema already covers.

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?

An output schema exists, so enumerating return fields is not strictly necessary, but the description still covers the decision-critical facts an agent needs: price, data origin, no-key access, and parameter preference. Nothing essential to invoking the tool 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% and both parameters are already documented in the input schema, including the alias relationship and accepted symbol aliases. The description's 'Prefer symbol; pair is accepted as alias' merely restates that schema content, so the baseline of 3 applies.

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 and source — Kraken Futures perpetual funding for PF_XBTUSD/PF_ETHUSD — and enumerates the metrics returned, so an agent knows exactly what it gets. It does not explicitly contrast itself with hl_funding_snapshot, though the 'Kraken Futures' framing implicitly separates it from the Hyperliquid sibling.

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?

'Prefer symbol; pair is accepted as alias' gives concrete parameter guidance, and 'Public API only — no keys' tells the agent no auth setup is needed. However, there is no explicit when-to-use/when-not guidance relative to basis_snapshot or hl_funding_snapshot, so selection between siblings is left to inference.

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