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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open-world), so the bar is lower. The description adds genuinely non-structured facts: pricing at $0.003/call or a Carry key, and that binning is by UTC weekday. It stops short of explaining what the response actually contains beyond the cryptic 'collapses_on_weekend' token.

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?

Two compact sentences with the core output dimensions front-loaded and no filler. The only weakness is unexplained internal jargon ('collapses_on_weekend') that reads like a leaked field name rather than prose.

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 0% parameter documentation, the description is the only source of truth, yet it omits the meaning of 'days', the shape of the returned calendar (per-weekday rows? APR units?), and any differentiation from the many sibling carry tools. Pricing and timezone are covered, but key calling details are not.

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 must carry parameter meaning. It clarifies the dex-vs-coin choice ('per dex (or one coin)') but leaves 'days' (integer, 7–120) entirely unexplained — the agent cannot tell whether it is a lookback window, a bucket count, or a limit.

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?

Names the specific resource and dimension: funding APR binned by UTC weekday, per dex or per single coin, plus a weekday-vs-weekend comparison and a 'collapses_on_weekend' flag. That is concrete enough to distinguish it from generic siblings like 'calendar', though it never explicitly contrasts itself with carry_funding_matrix or carry_history.

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 closing sentence 'Use for weekday/weekend funding patterns per dex or coin' gives a usage trigger, but there are no exclusions or named alternatives despite many adjacent carry_* tools (carry_funding_matrix, carry_history, carry_regime) that an agent could confuse it with.

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