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

With no annotations provided, the description carries the full behavioral burden. It does disclose a meaningful constraint: no WHOIS or ownership lookup is performed. However, it does not describe failures, side effects, return behavior, or how non-host parameters are treated, so transparency is only partial.

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 a single, front-loaded sentence with no filler. It is efficient, though slightly too sparse for the complexity implied by the seven-parameter input 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?

Given the schema has seven varied parameters, no annotations, and no output schema, the one-sentence description is insufficiently complete. It fails to clarify the relationship between the declared hostname-splitting purpose and the unrelated-looking parameters, and it does not explain what the result of the split looks like.

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?

The schema descriptions already cover all seven parameters, so the baseline is 3. The description adds that 'host' is split into labels, but it never explains why params like ref, url, city, feed, json, and path appear in a domain-shape tool, leaving the agent uncertain which parameter is actually meant to be used.

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 clearly uses a specific verb ('Split') with a precise resource ('a hostname') and a defined outcome ('into labels'). The qualifier 'without WHOIS or ownership data' adds a useful boundary. It loses a point for not stating the return format and for not acknowledging the other parameter types in the schema.

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?

No explicit guidance is given for when to use this tool versus its siblings like normalize-url, validate-json, github-repo-shape, or jira-key-shape. The only implicit trigger is 'hostname', but there is no when-not or alternative-selection guidance beyond the WHOIS caveat.

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