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

Adds real behavioral context beyond the annotations: a per-call charge of 0.01 USD, x402 payment mechanics, and the fact that repeated calls incur a new charge and can return different data. The 'annotation basis' sentence largely restates what readOnlyHint=false and idempotentHint=false already declare, but the cost and charge-per-call detail is genuinely new.

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?

Payment and purpose are front-loaded, which is good, but the third sentence is meta-commentary justifying annotation values that the agent already sees in the structured fields. That sentence spends words on restating structured data rather than on new guidance.

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?

For a zero-required-param, single-argument tool with full annotation coverage and no output schema, the description covers cost, payment flow, and freshness adequately. The main gap is that it doesn't sketch the payment handshake end to end (call without signature, then retry with one), which the schema only hints at.

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?

Only one parameter and the schema documents it at 100% coverage, including the 'omit to receive payment requirements' behavior. The description reinforces the paid flow but adds no syntax or format detail beyond the schema, so 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 verb and resource ('options-radar scan') plus the freshness qualifier 'on-demand fresh', which implicitly contrasts with the cached sibling. It stops short of naming mnemos_options_cached explicitly, so an agent must infer the distinction from the word 'fresh'.

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?

'On-demand fresh' plus the paid/cost framing implies when to reach for this over a cached read, but the description never states the condition or names the alternative. An agent has to infer that mnemos_options_cached is the cheaper choice when freshness is not required.

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