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

Goes well beyond the annotations by disclosing auth requirements ('Needs a person's key') and two concrete failure modes: check before proof propagates returns claimed false, and DNS records can take minutes to appear. Annotations only say readOnly=false, destructive=false, openWorld=true; the description supplies the operational nuance an agent needs to avoid misinterpreting a false result.

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?

Labeled sections (When/Instead/Inputs/Returns/Fails) front-load purpose and keep each line load-bearing. The telegraphic phrasing is dense but not wasted, and nothing is buried at the end.

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 compensates by enumerating both return shapes (start: site, record, dns, file, note; check: site, claimed, how). Combined with the failure-mode and auth notes, an agent has everything needed to sequence the two-step flow correctly.

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 baseline is 3, but the description adds real meaning: it ties `start` to producing a record/file and `check` to verifying and adding the site, and clarifies `site` is a bare domain like example.com. This is substantive semantics beyond the enum labels, though it stops short of exhaustive per-parameter detail.

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 ('Claims a site for the person') and immediately explains the mechanism: a TXT record or file as proof, then a verification check. The two-phase nature is spelled out, which distinguishes it from every read-only sibling in the list.

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?

Explicit 'When:' clause ties it to private site data (rivals, citations, proposals), and 'Instead:' clauses route to clickd_signup for a key and clickd_site for public reports that need no claim. Both the use condition and the alternatives are named outright.

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