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

No annotations, so the description must carry the load; it does disclose read-only behavior, the keyless CDX backend, and that each snapshot comes with a link. It omits failure behavior (what happens when a domain is unarchived), rate limits, or output shape beyond the link.

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?

One dense sentence followed by a two-word safety tag; the purpose and sibling disambiguation are front-loaded with 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?

For a single-param lookup with no output schema, the description covers purpose, sibling disambiguation, backend, and read-only safety. Slightly short on what the response contains when no captures exist, but adequate.

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% with a single required 'domain' string, and the description's only parameter-relevant hint is 'a domain,' adding nothing beyond the schema. Baseline 3 for high coverage.

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 (report) and resource (first and most recent captures of a domain in the Wayback Machine), and explicitly distinguishes itself from sibling wayback_urls by naming what that tool does (lists archived URLs).

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?

Frames the tool as a site-age / history signal and names the alternative (wayback_urls) for listing URLs, giving a clear selection rule. No explicit when-not conditions, but the intended use context is unambiguous.

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