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

It discloses that values are discarded, which is a key side effect, and the schema's optional-string parameters hint at a harmless read-only operation. However, since no annotations are provided, it does not fully disclose error behavior, return value, or what happens with zero keys.

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 two-sentence description is extremely concise and front-loaded, with no filler or redundant content.

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 no output schema, the description should state the return value and input format more explicitly. 'Count keys' implies an integer count, but the description does not explain how to supply the object given the parameter list, leaving some ambiguity.

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 description says values are discarded but does not clarify that the nine listed parameters are simply possible top-level keys and that none are required. The individual parameter descriptions in the schema are misleading (e.g., 'json' says validate) and do not match the count-keys behavior.

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 counts keys in a JSON object and that values are discarded, which establishes the core operation. It is slightly less clear how the object is supplied given the flat parameter list, but the purpose itself is unambiguous.

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 is given about when to prefer this tool over related siblings like validate-json or search-query-len. The description implies counting-key use cases but does not state alternatives or prerequisites.

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