Canonical host check (www, https, trailing slash)

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral detail beyond that: it returns the full redirect chain for each variant, identifies which variants are wrong, and states that no API key is needed.

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?

The description is front-loaded with the core purpose, then briefly explains why the check matters, gives concrete context, and states the return value and auth requirement. Every sentence earns its place and there is no redundancy with the title or schema.

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?

Despite having no output schema, the description explicitly states what is returned ('full redirect chain') and what judgment is made ('says which ones are wrong'). Combined with the fully documented schema and strong annotations, an agent has everything needed to call and interpret this tool 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 description coverage is 100%, so the schema already documents both parameters and their formats. The description reinforces the 'home page' default and the domain scope, but it does not add meaningful semantics beyond what the schema provides, which matches the baseline for full coverage.

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 names a specific verb and resource: checking that all http/https, www/bare, and trailing-slash variants converge on one canonical address. It clearly distinguishes this from sibling tools by enumerating exactly which URL variants are tested.

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?

The description gives clear context for when this tool is useful, specifically calling out Cloudflare Pages and WordPress migrations as common failure scenarios. It does not explicitly name alternatives or exclusions, but the domain of canonical-host redirect checking is unambiguous enough that an agent can infer when to invoke it.

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