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

With no annotations, the description carries the full burden, and it does disclose genuinely useful operational context: a per-call price of $0.002 in USDC on chain eip155:8453, which the agent cannot learn from the schema. It still omits the payment/auth flow (how the x402 payment is settled) and any rate-limit or error behavior, so it is good but not 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?

The return values are front-loaded in a single tight sentence, followed by use cases and pricing. Nothing is redundant, though the appended price clause is dense enough to slightly interrupt the flow.

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 tool with no output schema, the description usefully enumerates the returned fields and discloses cost, which is the main thing an agent needs before spending money. Payment mechanics and failure modes remain unstated, keeping it short of fully complete.

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?

There is a single parameter with 100% schema description coverage, so the baseline is 3. The description adds only marginal meaning beyond the schema ('any URL' vs. the schema's 'URL or domain'), giving no format, normalization, or edge-case guidance.

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 and resource ('Query the Internet Archive's Wayback index for any URL') and enumerates exactly what comes back: first archive date, most recent snapshot, span in years, recent captures. This clearly separates it from siblings like dev_url_reader and live_url_metadata, which fetch current page content rather than historical snapshots.

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?

Names three concrete situations ('fact-checking page history, finding deleted content and due-diligence'), which gives the agent a clear positive trigger. It stops short of naming an alternative tool or stating when not to use it, so it falls below the explicit routing bar.

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