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

With no annotations provided, the description carries the full burden of behavioral disclosure, but it only states that captures exist in the index. It does not say whether this is a read-only lookup, what the output contains, whether pagination or rate limits apply, or how the query affects the result.

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 front-loaded, but it repeats 'Common Crawl' twice and is under-specified. A single efficient sentence is fine, but this one lacks enough operational detail to be considered appropriately sized.

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 tool has an output schema, so return-value documentation is not necessarily required in the description. However, with no annotations, no parameter semantics, and no usage guidance, the description is incomplete for confident invocation, especially given a large sibling list with overlapping archive tools.

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 provides no description for the 'q' parameter and schema coverage is 0%. The description mentions 'a domain', which hints that 'q' is a domain, but it does not explicitly map 'q' to the parameter, specify format (bare domain vs URL), or explain the empty default behavior.

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 the resource ('Common Crawl index') and the subject ('a domain'), but 'Captures of a domain' is a noun phrase with no explicit action verb, so the operation is ambiguous: list captures, lookup index records, or fetch capture metadata? It also does not distinguish itself from archive-related siblings like cdxwayback, wayback, or archiveorg.

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?

No guidance is given on when to use this tool versus the many archive and domain-lookup siblings. There are no stated selection criteria, no exclusions, and no examples, so an agent must guess when Common Crawl is the right choice.

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