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

Annotations already cover readOnly/destructive safety. The description adds data provenance (Bybit-primary/Binance-fallback) and a payment requirement (USDC on Base), which are non-obvious behavioral constraints. It does not cover rate limits or failure modes, so not a 5.

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?

Three sentences, front-loaded with the wrapper identity and use condition. No redundant restatement of schema or annotations.

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?

A simple one-parameter read tool with an output schema and annotations. The description supplies alternative routing, data source, and cost context, leaving nothing needed to invoke it correctly missing.

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 symbol parameter is fully documented there. The description mentions output format (decimal and percentage) but adds no input parameter semantics beyond the schema. Baseline 3.

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 (funding rate value) and distinguishes it from sibling derivatives.funding_rate by listing the fields it omits (mark_price, index_price, open_interest_usd). An agent can tell the two tools apart without opening either 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?

Explicitly says 'use this when you only need the funding rate number itself' and names the alternative tool (derivatives.funding_rate). The when-to-use condition is front-loaded and unambiguous.

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