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

Annotations already declare readOnlyHint and openWorldHint, and the description goes well beyond them: private addresses are refused, robots.txt is obeyed, the free tools' hourly allowance applies, and no key is needed. The 'Returns' and 'Fails' lines tell the agent what comes back and what the failure modes are.

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 organized under When/Instead/Inputs/Returns/Fails labels so each sentence is scannable. No filler beyond the brief 'as the free tools do' framing.

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 describing the return shape (findings with a one-word state and remediation). Failure behavior, rate limits, and auth requirements are all covered, so an agent has everything needed to call it 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 the enum and url are already documented; the description still adds real meaning by specifying that ssl consumes only the host portion and locations expects the brand's site rather than a page. Those per-kind input quirks are not derivable from the schema alone.

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 qualifiers: 'Checks one live address now' and enumerates the five check kinds. The word 'one' plus 'now' distinguishes it from the batch-oriented siblings without requiring the schema to be opened.

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:' line scopes it to before/after a fix on a single page, link or host, and an explicit 'Instead:' line routes whole-site checks to clickd_rescan/clickd_changes and last-read snapshots to clickd_pages. Both the use case and the exclusions are named.

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