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

Annotations already establish read-only, idempotent, open-world behavior, so the bar is lower; the description still adds real substance: rates are normalised to 8 hours, venues are enumerated, the aggregate is open-interest weighted, and the sign convention ('Positive = longs pay shorts') is defined. It stops short of noting caching or rate limits, but that is a minor omission.

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?

Front-loaded with the resource, then the two modes, then the sign convention. Every sentence carries information; the venue enumeration is slightly list-heavy but justified since it defines the aggregate's scope.

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 must describe the return shape and it does: per-venue normalised rates plus an OI-weighted aggregate in coin mode, and ranked extreme payers in default mode. An agent has everything needed to call and interpret the result.

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 the schema already documents both parameters, making 3 the baseline. The description reinforces the coin/no-coin dichotomy, but adds no syntax, units, or interpretation for 'limit' beyond what the schema states.

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?

States a specific resource (perp funding rates) and spells out the two distinct operating modes: per-venue + OI-weighted aggregate when a coin is given, and top positive/negative payers when not. No sibling tool covers funding rates, so it is trivially distinguishable from the list.

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 description explicitly conditions behavior on whether a coin is supplied, telling the agent which mode to expect. It does not name an alternative sibling or state when another tool would be preferable, but for this tool the mode selection is the key guidance and it is fully covered.

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