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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds real behavioral context beyond that: the fallback to an in-progress crawl, the meaning of mixed content (insecure http assets on an https page), and the internal/external counting scheme. It does not mention rate limits or pagination, but those are minor here.

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 main behavior is front-loaded in a single (long) sentence, followed by a short routing instruction and a docs link. Dense but every clause carries information; the parenthetical definitions are a touch heavy.

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?

An output schema exists, so return-value explanation is unnecessary, and the description covers scope, fallback behavior and the sibling alternative. The only gap is explicit guidance on choosing between the two report modes, which an agent can infer from the enum descriptions.

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 description coverage is 100%, so report, monitor_id and limit are already fully documented with types, bounds and an enum. The description adds semantic color about what each report value represents but no new syntax or format detail, so the 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 concrete verb and resource ('Get what Oh Dear's crawler found on a site during its most recent crawl') and enumerates the two shapes of the result (mixed content vs. internal/external URL breakdown). It also explicitly distinguishes itself from the sibling get_broken_links, so an agent can route without opening a schema.

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 the alternative explicitly ('For the broken links themselves, use get_broken_links') and clarifies that an in-progress crawl is used as a fallback when none has completed. It stops short of stating when to prefer mixed_content over crawled_urls, leaving that to the enum descriptions.

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