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

No annotations are provided, so the description carries the full burden. It discloses that values are discarded, which is good, and explains that the JSON input is read-only. However, it doesn't specify if the tool accesses any external state (e.g., memory storage) or if it has side effects. Given the large schema with many parameters that are noted as 'discarded', the description does hint at a read-only nature but could be more explicit.

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: one sentence. It front-loads the core action. However, it is so terse that it sacrifices utility for brevity, falling short of what a richer description could provide.

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?

Given the tool's complexity—9 parameters, 0 required, no output schema—the description is insufficient. It does not clarify the return format, how the count is returned, what happens with invalid JSON, or how the other parameters relate to 'memory'. The description is far from complete for an agent to use correctly.

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 described, but many descriptions are just 'discarded after X', which adds little meaning beyond the schema. The description text itself does not elaborate on the 'json' parameter, which is central to the tool's purpose. It adds minimal value over the schema since most parameters are irrelevant to the tool's named function.

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 ('Count') and resource ('keys in a JSON object'), and highlights that values are discarded. However, the tool name 'memory-key-count' is vague and the description lacks clarity on what 'memory' refers to—it likely relates to workspace memory, not just any JSON object. It does not distinguish itself from 'validate-json' or 'domain-shape' siblings, which also operate on JSON-like structures.

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?

The description provides no guidance on when to use this tool over others. Given the long list of sibling tools with overlapping purposes (e.g., validate-json, domain-shape), the lack of any when-to-use or when-not-to-use instructions leaves an agent guessing. It does not mention prerequisites or alternatives.

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