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

Annotations already cover read-only, idempotent, open-world and non-destructive traits, so the description is free to add ordering ('newest first'), the limit cap, and the status filter. Most valuable is the caveat that a verdict on a final_url-only row belongs to the submitted host, not this domain – genuine interpretive context that annotations cannot convey.

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 dense sentences with no filler; scope, ordering and filtering are front-loaded before the matched_on caveat. The second and third sentences are clause-heavy and slightly hard to parse on first read, which keeps it out of 5 territory.

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?

With an output schema present, return values need not be described, yet the description still explains the critical row-level 'matched_on' semantics. Combined with scope, ordering and filtering, an agent has enough to call it correctly; only the status value domain and sibling routing are missing.

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 0%, so the description must carry the load. It adds meaning for 'limit' ('up to limit') and 'status' ('filters by scan status') and implies 'domain' matches subdomains, but it never enumerates valid status values or explains the default limit, leaving gaps.

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 with scope: 'List the recent scans of a domain and its subdomains, newest first, up to limit.' The domain-scoped framing implicitly separates it from global siblings like get_recent_scans, but no sibling is named explicitly, so it stops short of a 5.

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 implied by the scope statement (use this to list recent scans for a given domain), but the description never says when to prefer this over get_domain_history, get_domain_stats, or search_scans, nor what prerequisites exist. The matched_on note is interpretation guidance rather than routing guidance.

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