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 genuinely new operational context: the call costs $0.005 USDC via x402, which an agent must know before invoking, plus what the response contains (page text and a snapshot list).

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?

Three sentences, front-loaded with what it returns, then the use case, then cost. Tight and well-ordered, though 'See what a page said before it changed' is slightly redundant with the first sentence.

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?

No output schema exists, but the description covers the return shape (snapshot, page text, recent snapshots) and the payment requirement. For a 3-parameter read-only tool this is close to complete; only the url parameter's accepted formats are unaddressed.

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 67% (url undocumented, date and text documented). The description corroborates the text parameter by mentioning the archived page text and notes the date-relative behavior, but adds no format or syntax detail beyond the schema. Baseline 3 is appropriate.

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+resource: it returns the Internet Archive snapshot closest to a date, including archived page text and a recent-snapshots list. This clearly distinguishes it from live-fetch siblings like scrape, crawl, and url_metadata without the agent needing to compare schemas.

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 'See what a page said before it changed' implies the use case (historical/archived content) but names no alternatives or exclusions. An agent is left to infer that scrape/crawl are for live content and this is for archived versions.

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