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

With no annotations, the description carries the full burden of behavioral disclosure. It discloses one trait: 'Values discarded,' which indicates it only counts keys and ignores values. However, it does not mention side effects, error conditions, what happens with malformed JSON, or the return format. The parameter descriptions in the schema say some are 'discarded after the shape check,' but the tool description does not integrate that context. The disclosure is minimal and incomplete.

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 very concise at two sentences, which is structurally front-loaded with the core action. However, conciseness is achieved at the expense of essential information—the tool omits how to provide the JSON object. It is not verbose, but it is under-specified. It earns a middle score because it is efficient yet lacks critical guidance.

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?

For a tool with 9 parameters, no required parameters, no output schema, and no annotations, the description is severely incomplete. It does not explain how to invoke the tool, what the return value looks like, or which parameter is relevant. An agent cannot correctly call this tool based on the description alone. The description is far from the minimum viable for this complexity.

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?

Although schema coverage is 100%, the tool description adds no meaningful linkage between the parameters and the tool's purpose. It never mentions which parameter is the JSON object to inspect. The schema descriptions are also terse (e.g., 'JSON text to validate; discarded after the check'), but the tool description does not build on them. With 9 optional parameters and no required ones, the agent has no clue which parameter to pass. The description adds no value beyond the schema and actually leaves the mapping ambiguous.

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 action: 'Count keys in a JSON object.' That is a clear verb+resource, and it distinguishes from siblings like validate-json. However, it fails to specify which of the 9 parameters holds the JSON object, leaving the actual invocation ambiguous. The tool name 'memory-key-count' suggests a narrow scope, but the description does not clarify that the 'json' parameter is the intended input.

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 vs alternatives. It does not mention alternatives, prerequisites, or context. The description gives no hint about whether to use this instead of validate-json or other JSON-related tools. An agent is left to guess when this tool is appropriate.

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