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

Goes well beyond the annotations by disclosing a 28-day cache window with query string and fragment ignored, the exact 409 public_scan_exists payload shape (error.meta { slug, statusUrl, pageUrl }), the fact that cached/running lookups ignore viewport, locale and timezone, and the 503 public_scans_disabled case. For a mutation tool (readOnlyHint=false) this is unusually rich operational disclosure.

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?

Front-loaded with the core action, then densely packed with outcome semantics in a small number of sentences. The parenthetical '(public, no API key)' is slightly redundant with the following sentence, but nothing is wasted.

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 no output schema, the description carries the burden and does explain status codes and the statusUrl polling loop. It leaves the success-response payload shape (where statusUrl/slug come from on a fresh enqueue) implicit, which is a small but real gap for an agent parsing the response.

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 100%, so the baseline is 3, but the description adds real meaning: it tells the agent that viewport, locale and timezone do not affect cache or in-flight matching, which is semantics the schema cannot express. It stops short of explaining whether those parameters affect the resulting scan at all.

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 states a specific verb and resource ('Queue the free homepage scan of one URL') and qualifies it as 'public, no API key', which separates it from the authenticated trigger_scan sibling. It does not name get_public_scan or get_target as the follow-up/alternative tools, so differentiation is good but not complete.

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?

Clear prerequisites and context: free homepage scan, one URL, no API key. It explains what happens for each outcome (cached 200, in-flight 409, operator-disabled 503) and instructs the caller to poll statusUrl, but it never explicitly contrasts this with trigger_scan or rerun_target_scan for non-public scans.

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