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

Annotations are entirely absent, so the description carries the full disclosure burden. It reveals one behavior — "Values discarded" — but is silent on error handling for invalid JSON, whether keys are counted at top level or nested depths, the return shape, and the retention implications hinted by the tool's "memory" name.

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?

Eight words across two sentences, with the core action front-loaded and the key qualifier immediately following. Every word earns its place with no fluff — exemplary minimalism, even though other dimensions pay the price for the brevity.

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 heterogeneous parameters, zero annotations, and no output schema, the description leaves the parameter-to-operation mapping unresolved — an agent cannot tell which parameter carries the JSON or what happens when multiple are provided. The return value (a key count) is only implied, and failure behavior for malformed JSON is undocumented.

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 coverage is 100%, which sets the baseline at 3, and the description adds no parameter-level meaning. It never identifies which of the nine heterogeneous parameters (ref, url, city, feed, host, json, path) supplies the JSON object to count, and the schema's "JSON text to validate" wording sits awkwardly against the description's counting intent.

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 verb and resource — "Count keys in a JSON object" — which is instantly distinguishable in action from the sibling list, and "Values discarded" sharpens the scope. However, it never explicitly contrasts itself with adjacent tools like validate-json, so differentiation is implicit rather than stated.

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 when-to-use or when-not-to-use guidance is offered; the two sentences are purely definitional. With 27 siblings including validate-json and other JSON-adjacent tools, an agent has no basis for routing between this and an alternative.

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