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

Annotations already mark it as read-only, idempotent, and non-destructive, so safety is covered. The description adds useful behavioral context: it crosses three free public sources, returns a max-spread and carry direction, and carries a $0.03 USDC charge, which is not encoded in the annotations.

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 function, followed by pricing and source details. It is slightly redundant ('3 free public sources crossed' repeats Binance/Bybit/OKX) and the punctuation is choppy, but no content-free filler is present.

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 rich annotations, an output schema, and zero required parameters, the description covers the essential facts: what signal it produces, which venues are crossed, that it is a signal rather than a wrapper, and what it costs. It does not elaborate on input flexibility or refresh behavior, but these are less critical given the schema and optional input.

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% for the single 'input' parameter, but the schema only describes it as 'parametros del producto (JSON o texto)' without concrete fields, syntax, or examples. The description does not add parameter-level guidance, so it remains at the baseline 3 without compensating for the ambiguity.

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 defines the tool's purpose: it computes perp funding rate spreads across Binance, Bybit and OKX for top pairs, with the max spread and carry direction. It also explicitly says 'not a wrapper,' distinguishing it from generic wrappers or aggregators among the sibling tools.

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 phrase 'Funding arb signal' gives a clear intended use case: agents should select this tool when they need a cross-exchange funding-rate arb signal. It provides useful context about the three sources and the theoretical carry direction, though it does not explicitly name alternatives or exclusion conditions.

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