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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered; the description adds real value by disclosing that the query is bounded and that results are downsampled to one earliest capture per year. Explicitly ruling out total capture counts is exactly the kind of behavioral caveat annotations cannot express.

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?

Two short sentences with the result shape front-loaded and the limitation trailing, with no filler. 'Bounded' is left undefined, which is a minor ambiguity rather than wasted wording.

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?

With an output schema present the description need not explain return values, and the sole parameter is fully documented in the schema. What remains — the sampling behavior and the absence of counts — is stated, making the definition sufficient for correct invocation.

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 coverage is 100% and the single domain parameter is fully documented in the schema (bare hostname, no scheme/path/port/IP). The description adds no further meaning about the parameter, 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?

The description names a specific verb and resource ('Fetch one bounded Internet Archive CDX query') and states the result shape ('earliest capture sample for each year'), so the agent knows this is a CDX capture lookup rather than a general availability check. It stops short of naming the sibling domain_wayback_availability, leaving the distinction implicit.

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?

The phrase 'one bounded ... query' implies a single, scope-limited call, and 'Total capture counts are not returned' warns of a limitation without pointing to the tool that would supply counts. There is no explicit when-to-use or when-to-prefer-domain_wayback_availability guidance.

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