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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real value beyond them by disclosing the return shape (value, value_classification, optional history[]) and a concrete example response with source. It does not mention rate limits, but the per-call price line covers the cost dimension.

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-loads the definition, then uses labeled blocks (Use when / Not for / Returns / Example) with zero filler. Every line — including the example response and price — earns its place for an agent deciding whether to call.

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?

No output schema exists, but the Returns line and example response fully describe the payload, and the routing clauses handle the alternatives. Nothing an agent needs in order to call this correctly is 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 'limit' parameter is fully documented in the schema (default 1, max 30). The description only gestures at it via 'optional history' and adds no format or syntax beyond the schema, so the baseline 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?

States a specific resource ('Crypto Fear & Greed Index') with its scale semantics (0=extreme fear, 100=extreme greed) and scope ('optional history'). It names the sibling tools it is not (crypto_news, funding_rates), so an agent can distinguish it 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?

Explicit 'Use when' clause defines the triggering condition (gauge overall crypto market sentiment), and an explicit 'Not for' clause routes away to the correct alternatives for token-specific sentiment. Both the positive and negative selection criteria are stated.

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