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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds value beyond that by disclosing the multi-exchange source set, the returned fields (funding_rate_pct, annualized_rate_pct, sentiment), and how sentiment should be read. It still omits failure modes or rate-limit behavior, but with annotations present this is solid.

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 Use when / Not for / Returns structure is front-loaded and scannable, with no redundant sentences. The full example JSON is somewhat long but provides concrete payload shape, and the price line is minor boilerplate.

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?

There is no output schema, so the description carries the return-value burden and does so completely: named fields, per-exchange granularity, sentiment values, and a sample response. Combined with the explicit routing to siblings, an agent has everything needed to call it correctly.

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% and the single optional 'asset' parameter is fully documented in the schema (symbol, empty for all majors). The description adds no syntax or defaulting detail beyond that, so the baseline of 3 applies.

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 names a specific verb+resource ('Get perpetual futures funding rates') and enumerates the exact sources (Binance, Bybit, OKX). An agent can distinguish this from siblings like open_interest or market_snapshot without opening any schema.

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 explicitly states 'Use when' (gauge leveraged sentiment or cost of holding a perp) and 'Not for' (open interest / long-short ratio → open_interest; combined verdict → pre_trade_check). Alternatives and the conditions selecting them are named directly.

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