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

With no annotations, the description carries the full behavioral burden. It does disclose two useful traits: the operation is a lookup (read-only by nature) and it is free, which matters for quota/cost planning. It omits rate limits, authentication requirements, and what happens for URLs with no snapshot, so the disclosure is partial rather than complete.

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 sentence plus a one-word cost note — nothing is wasted and the core question is front-loaded. The 'Free.' fragment is slightly abrupt but conveys a real decision-relevant fact efficiently.

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 one-parameter, no-output-schema lookup tool, the description covers the essentials: what is checked and what information comes back (existence plus timestamp). Remaining gaps — URL format and no-snapshot behavior — are minor for a tool this simple.

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 0% and the single property is a bare string, so the description is the only source of parameter meaning. It establishes that the parameter is the URL to look up, but adds no format requirements (absolute URL, scheme handling, encoding) that would prevent malformed calls.

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 resource (the Wayback Machine) and the exact question it answers: whether a given URL is archived and when. The verb is phrased as a question rather than a directive, but an agent can still immediately tell what the tool does and that it is distinct from every sibling (none of which touch web archives).

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?

Usage is only implied by the question itself — call it when you need archive status for a URL. There is no explicit when-to-use, when-not-to-use, or routing to an alternative (e.g., a live-fetch tool like fetch_free) when the page is not archived. The single word 'Free' hints at a cost trade-off but does not constitute guidance.

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