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

With no annotations, the description carries the disclosure burden and does so for the most consequential trait: it is a paid call at $0.001 via x402/USDC Base, which an agent must know before invoking. It also states the return contents. It does not explain the payment handshake, failure behavior, or whether repeat calls are re-billed, which keeps it short of 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?

A single dense sentence that front-loads the cost constraint before the data description — the right ordering for an agent deciding whether to spend money. Minor redundancy in 'today + yesterday + week ago + 10-day history', since the first three are contained in the last, costs it a point.

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 and no annotations, yet the description covers the cost, the returned data, and the scale interpretation, which is enough to call it correctly. Freshness/cadence and payment-failure behavior are the remaining unknowns, but they are secondary for a zero-arg read.

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?

The tool takes zero parameters, so per the baseline there is nothing for the description to disambiguate, and it correctly adds none. No misleading hints about optional filters are introduced.

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 concrete resource (crypto Fear & Greed index) and precisely enumerates the payload: today, yesterday, week-ago and 10-day history, with the 0-100 scale meaning. An agent can distinguish this from get_market_pulse or get_crypto_price purely from the text.

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?

'Market sentiment signal for trading agents' implies a use context but gives no explicit when-to-use/when-not guidance and never names an alternative among the many crypto siblings. The caller must infer that this is a sentiment read rather than a price or news tool.

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