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

Annotation Contradiction: readOnlyHint is true, but the description explicitly states 'Paid $0.01 USDC exact on Base' and provides a payTo address, indicating a financial side effect. This directly contradicts the read-only annotation, and the added cost/source details cannot compensate for the inconsistency.

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 short and dense, but poorly front-loaded: payment details precede the actual purpose. 'Not investment advice' is boilerplate, and the ordering makes it harder for an agent to quickly identify what the tool does.

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?

The description covers cost, payee, data source, and parameter limits, which is useful for a simple tool. However, there is no output schema and no description of the response shape, so the agent cannot know what the tool returns beyond the vague 'Crypto Fear & Greed Index'.

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 schema already documents the limit parameter with 100% coverage, including range and default. The description's 'Optional limit=1..30 (default 1)' adds no meaningful semantics beyond repeating the schema.

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 identifies the resource as the 'Crypto Fear & Greed Index via public alternative.me', which is specific and distinct from the sibling tools. It lacks an explicit retrieval verb and the opening 'Paid $0.01 USDC...' clause initially obscures the core purpose.

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?

There is no guidance on when to choose this tool over siblings like price, quote, or crypto_news. The description implies it is for fetching the Fear & Greed Index, but it provides no exclusions, alternatives, or situational context.

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