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

Annotations already cover read-only/open-world, and the description adds substantial non-annotation behavior: paid access at $0.002 USDC per successful call, x402 payment over Base/Solana/Arc, and the fact that failed calls are not charged. It also discloses the attribution requirement imposed by alternative.me, an obligation the agent would otherwise not know about.

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 compact sentences: what it returns, where it comes from plus the attribution duty, then what it is not. Pricing and payment rails follow immediately. Front-loaded with the payload and no filler.

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?

Output schema exists, so return format need not be explained; the description still covers source, range, granularity, cost model, payment options, billing on failure, and attribution. Nothing an agent needs before invoking is absent.

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 single parameter 'days' is fully documented in the schema (1-30, default 7) and the description only repeats the ceiling with 'up to 30 previous days.' With 100% schema coverage the baseline of 3 applies; the description adds no format or edge-case detail beyond 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?

States a specific resource (Crypto Fear & Greed Index 0-100 from alternative.me), the exact payload (today's value and label plus up to 30 prior days), and the granularity (daily). It also explicitly rules out the misreading its 'jobs_' name invites with 'Not a job or salary dataset,' which is exactly the differentiation an agent needs among 60+ job-board siblings.

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?

Clearly signals the use case (crypto market sentiment, daily history up to 30 days) and negatives the wrong one (not jobs/salary data), which is the main confusion risk given the name. There are no true sibling alternatives to route between, so no exclusions or comparisons are missing, but there is no explicit 'use when' clause either.

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