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

Side-effect is summarized ('Changes nothing'). More importantly it discloses behavior the annotations cannot: the two discovery sources, the 90-day Search Console click window, the log-scoped hours window, and that each result carries hits plus a sitemap-derived suggested target.

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 purpose, then sources and constraints, ending on the no-mutation guarantee. Two dense sentences with no filler or repeated schema content.

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 and only four anonymous parameters, the description still explains what each result contains (hits and a suggested target), where data comes from, and the defaults. An agent has enough to call it correctly and interpret 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 schema already documents site, hours, server and min_hits. The description restates the hours default (168) and implies min_hits filtering but adds no syntax or semantics beyond the schema, so baseline 3 applies.

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?

Specific verb+resource+scope: 'Find the paths of a site on the user's server that answer 404'. It names its two data sources (crawler access logs and Search Console) and distinguishes itself from the redirects_apply/redirects_list siblings by being the discovery step that 'changes nothing'.

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 rather than explicit: it's clearly the diagnostic step that precedes redirect creation, and 'Changes nothing' signals it is safe to run first. But no sibling (e.g. redirects_list, redirects_apply) is named as an alternative and no explicit when/when-not condition is stated.

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