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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It claims to split hostnames but the parameters include many unrelated fields, and the description gives no hint of side effects (e.g., 'discarded after the check' implies no persistence, but the general behavior is unclear). It doesn't mention whether any inputs are actually used for the stated task or if the tool is a multiplexer that behaves differently per parameter. The description is too vague to set expectations.

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, which is concise, but it omits necessary information and is misleadingly brief for a tool with 9 parameters. It front-loads 'Split a hostname' but doesn't acknowledge the other use cases, so the brevity works against clarity. It earns a 3 for being short, but the structure fails to organize the tool's actual scope.

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 tool has 9 optional parameters, no output schema, and no annotations, the description is severely incomplete. It only mentions hostname splitting while the schema implies a multi-purpose validation tool. Without an output schema, the description should explain what the tool returns (e.g., a shape check result), but it says nothing. An agent cannot know what to pass or what to expect for most of the parameters. This is inadequate for a tool of this complexity.

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%, meaning each parameter has a description in the schema. However, the overall tool description does not add meaning beyond the schema; it actually contradicts the schema by implying the tool only handles hostnames while the schema shows it handles 9 distinct field types. The schema descriptions are self-contained, but the tool-level description fails to explain how parameters relate to the stated purpose, so the agent gets conflicting signals about what to pass.

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 states a verb ('Split') and a resource ('hostname'), but the purpose is misleading because the input schema accepts 9 unrelated parameters (URL, city, feed, JSON, path, zone, query) that have nothing to do with splitting hostnames. The tool name 'domain-shape' and the description suggest a narrow function, but the schema reveals it accepts arbitrary inputs for various checks, so the description under-specifies the actual behavior and doesn't distinguish it from siblings like 'normalize-url' or 'geo-hint'.

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 guidance on when to use this tool versus alternatives. With 29 sibling tools covering many of these inputs (e.g., 'normalize-url', 'geo-hint', 'validate-json', 'search-query-len'), the description provides no exclusions or selection criteria. The tool is a catch-all, but the description fails to explain when to use it instead of a more specific sibling.

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