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

The readOnlyHint annotation already establishes the safety profile, and the description adds useful behavioral context: it returns the 7-day median spread, duration above the repay-within-a-day threshold, and breakeven hours against four legs of fees. It also notes that assumptions are included in the answer, which helps an agent interpret results.

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 description is compact and front-loads the core purpose: widest funding-rate spread right now. It packs useful output details into a single dense sentence without wasted clauses, though the phrasing is slightly complex.

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?

Given the read-only annotation and the presence of an output schema, the description is sufficiently complete: it explains the scan purpose and key returned metrics. It does not cover sibling routing, but the structural fields carry the rest of the needed context.

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 100%, so both parameters (lang and limit) are already fully documented in the schema. The description does not add parameter-level meaning beyond what the schema provides, making the baseline 3 appropriate.

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 clearly states the resource: cross-exchange funding-rate spreads, specifically the widest spreads right now and the long/short leg construction. It is specific enough to distinguish from generic funding tools, but it does not explicitly differentiate itself from siblings such as pair_briefing.

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 implied by 'where the funding-rate spread between exchanges is widest right now,' giving a clear scenario for selecting this tool. However, it provides no explicit when-to-use, when-not-to-use, or alternative-tool guidance against siblings like pair_briefing or funding_history.

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