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

With no annotations, the description carries the entire burden. It does state a behavioral trait: it splits the host without doing WHOIS/ownership lookups, so agents know it performs no remote data enrichment. However, it doesn't disclose side-effects, permission requirements, how errors are raised (e.g., invalid hostname), or how multiple parameters interact. These remarks are useful but significant gaps remain.

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 short sentence with zero filler. It is front-loaded and each word contributes to the boundary, though it is so brief that important context about the broader parameter set is omitted. For what it does convey, the conciseness is excellent, but the content is not equally rich.

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?

The tool has 9 optional parameters, no output schema, and no annotations, yet the description only covers hostname splitting. It doesn't tell the agent what to pass when only e.g. 'url' or 'json' is provided, what the result shape looks like, or how errors are represented. The extra parameters and discard annotations suggest a broader shape-check role, but the description leaves that context entirely missing, making it under-specified for a rational caller.

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 already describes all parameters at 100% coverage, including the host parameter ('Public hostname') and direct discard annotations for several other parameters. The description does not add parameter-specific meaning beyond the schema, such as clarifying which parameter to pass or how it is used. Under a full-schema baseline, a 3 is the correct credit for not needing to repeat what the schema says.

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 action and resource: splice a hostname into labels. It also adds a useful boundary (rather than WHOIS/ ownership data), making it clear this is about lexical splitting, not metadata lookups. It doesn't explicitly place itself among sibling shape tools like figma-url-shape or github-repo-shape, but the single-verb message and the sentence 'purpose_home' sufficiently identify what it does.

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?

It implies when to use the tool (when you need a hostname's labels without resource-ownership data) but never names any sibling alternative or states conditions such as 'use domain-shape for this, uses fetch-status for that.' The negative caveat 'without WHOIS or ownership data' is an implicit exclusion, not an explicit usage rule. The guidance is valid but not fully actionable.

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