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

Annotations are not provided, so the description carries full responsibility for behavioral disclosure. The description mentions that the tool splits a hostname, hinting at a read-only operation,, but it does not state whether any parameters are discarded (even though the schema's descriptions indicate several are), nor does it clarify that only the 'host' parameter is relevant. The lack of clear behavioral expectations is a significant gap.

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 very short and to the point, with no unnecessary verbosity. The single sentence effectively states the core purpose and a key exclusion. It is well-structured for a description, though it could benefit from a bit more context about parameter usage.

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 9 parameters, lack of annotations, and no output schema, the description is grossly incomplete. It does not clarify which parameters are relevant, what the output is, or how to use it correctly. Even though the schema descriptions are rich (100% coverage), the description's lack of focus on the actual 'host' parameter and the tool's behavior leaves the agent under-informed. Significantly more guidance is needed for this multi-parameter tool.

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% (all parameters have descriptions), so the baseline is 3, but the description adds nothing about parameters. The description only mentions 'a hostname', whereas the schema lists 9 unrelated parameters. The schema descriptions do provide some meaning, but the description does not help the agent understand which parameters are actually used for the shape check, especially since most are marked as 'discarded'.

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 clear verb ('split') and a specific resource ('hostname'), and explicitly notes that it excludes WHOIS/ownership data,, which differentiates it from its name. However, the schema lists many unrelated parameters (e.g., 'city', 'feed', 'json'), making the tool's actual scope ambiguous. The description is coherent with the name, but the schema-wide parameter list undermines clarity.

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 a hint about what the tool does not do (no WHOIS/ownership), which is some context, but it does not specify when to use this tool versus the numerous siblings (e.g., 'browser-url-ok', 'figma-url-shape', 'file-path-ok'). It lacks explicit conditions that would help an agent select it over similar-looking tools. The alternative to use is not named.

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