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

No annotations are provided, so the description carries the full burden. 'Values discarded' is a real behavioral disclosure, but the description omits the return type, whether keys are counted at top level or recursively, error handling, and any side-effect or mutability information. This is thin for a description with zero annotation support.

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 extremely concise and front-loaded with the action ('Count keys'), immediately followed by a clarifying constraint ('Values discarded'). Every word earns its place with no filler.

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?

Despite full schema descriptions, there is no output schema and no annotations, and the description does not state what the tool returns or disambiguate which parameter should be treated as the object to count. An agent is left guessing between passing `json` as JSON text and supplying multiple optional keys as the object itself.

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 the baseline is 3. The description does not explicitly map the JSON object to the `json` parameter or clarify whether the count applies to the keys in the argument object or to the contents of the `json` string; parameter descriptions like 'JSON text to validate; discarded after the check' add ambiguity rather than resolving it.

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 ('Count keys') and a clear target ('JSON object'), plus a meaningful behavioral constraint ('Values discarded'). It is distinguishable from sibling validation/shape tools like validate-json because the focus is key counting rather than validation, though the 'memory' aspect in the tool name is left unexplained.

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 about when to use this tool versus alternatives, no mention of what to do with empty objects or invalid JSON, and no exclusionary notes like 'use validate-json instead'. Usage has to be inferred entirely from the name and description.

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