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

No annotations are supplied, and the description only says values are discarded. It does not state whether the operation is read-only, what side effects exist, or what happens on invalid input. Field-level notes in the schema hint at non-effects, but the tool description itself is silent.

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 short and front-loads the main action in the first sentence. The second sentence adds a useful qualifier about values, so there is little wordiness.

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 omits critical context: which parameter contains the JSON, what counts as a key, how to handle arrays or empty objects, return format, and error behavior. Without an output schema or further explanation, an agent cannot reliably call this 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?

The schema has nine optional string parameters with generic descriptions, but none clearly says 'JSON object whose keys are counted.' The 'json' field is described as 'JSON text to validate; discarded after the check,' which is inconsistent with counting keys, and the other fields appear irrelevant to the stated purpose.

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 action and target: count keys in a JSON object and discard values. However, it does not identify which of the nine optional input fields supplies the JSON object, so the purpose is only partially clear.

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 guidance on when to use this tool or how it differs from siblings such as validate-json, search-query-len, or other count/shape tools. No examples or selection criteria are provided.

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