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

The read-only and idempotent behavior is already conveyed by annotations. The description adds useful behavioral context beyond this: optional before/after ms-epoch cursors and limit, and the historical nature of the data. It doesn't contradict annotations, though it omits pagination direction and API limits that would be minor additions.

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 two sentences, with the core purpose front-loaded, then only relevant parameter context and a use case. No filler or repetition of the tool title.

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?

The tool has a simple schema, read-only annotations, and an output schema, so the description can rely on those. It covers the key inputs and use case, but would be more complete if it explicitly settled the meaning of `after` vs `before` in cursor terms or stated default result ranges.

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?

With 0% schema description coverage, the description compensates by explaining `before`/`after` as ms epoch cursors, `limit` as an optional numeric cap, and `instId` with a concrete SWAP example. This is meaningful but not fully exhaustive—'before' and 'after' directionality is not explicit, and default/limit behavior is unspecified.

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 identifies the resource ('OKX crypto exchange historical perpetual swap funding rates') and the exact instrument format ('SWAP', e.g. 'BTC-USDT-SWAP'). It differentiates from the sibling `funding_rate` by emphasizing historical data, making the purpose unambiguous.

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?

It gives a clear intended use context, 'funding cost analysis', and identifies the data scope. However, it does not explicitly mention sibling alternatives (e.g., `funding_rate` for current rates) or state when not to use this tool, so it falls short of full routing guidance.

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