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

The description only mentions hostname splitting but the schema includes many unrelated parameters (city, feed, json, etc.) with no explanation of how they interact or are ignored. This lack of disclosure about parameter handling makes the tool's behavior opaque and potentially misleading.

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, concise sentence that directly states the core function and a key exclusion. No unnecessary words or repetition.

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 description fails to account for the majority of parameters in the schema, creating a mismatch. It does not explain what happens to parameters like 'city' or 'json', leaving the tool's full context incomplete. The lack of an output schema or error handling notes further reduces completeness.

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 descriptions already cover all 9 parameters (100% coverage), so the tool description adds minimal value. It clarifies the overall purpose but does not explain relationships or which parameter is the primary input, meeting the baseline for high schema 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 clearly states the tool's primary action ('Split a hostname into labels') and explicitly excludes WHOIS/ownership data, making its purpose distinct and straightforward. It aligns well with the tool name 'domain-shape'.

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 provides no explicit guidance on when to use this tool versus alternatives, though the phrase 'without WHOIS or ownership data' hints at a limitation. It does not mention scenarios where this should be preferred or avoided, leaving the agent to infer usage from the name alone.

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