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

No annotations are provided, so the description carries the full disclosure burden. It adds one useful behavioral fact ('body discarded'), implying content is not persisted, but says nothing about returns, errors, permissions, or what a 'count' result looks like for a nine-parameter tool.

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?

A single front-loaded fragment with no wasted words, but it reads as a terse label rather than a sentence, and its brevity stems from under-specification rather than efficient communication.

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?

With nine unrelated parameters, no annotations, and no output schema, the description must carry most of the burden, yet it covers only a vCard FN check and leaves the purpose of url, city, feed, host, json, path, zone, query, and ref entirely unexplained. It is grossly incomplete for the tool's actual surface.

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%, so each parameter is already documented in the schema (including the 'discarded after the check' semantics). The description adds no parameter-level meaning beyond this and mentions no parameter that exists in the schema, so the baseline of 3 applies.

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 specific operation on a specific resource (count FN fields in a vCard) plus a behavioral detail (body discarded). However, it describes only one narrow facet while the schema exposes nine unrelated parameters (url, city, feed, host, json, path, zone, query, ref), so an agent cannot tell from the description what the tool actually validates overall, and no sibling is named or excluded.

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?

There is no when-to-use guidance, no exclusions, and no reference to alternatives such as validate-json, file-path-ok, iana-zones, or the other shape-check siblings. The agent must infer that this tool applies to vCard FN counting 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.