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

With no annotations, the description carries the burden of behavioral disclosure. It explicitly says 'Values discarded,' which is a meaningful behavioral trait, and the schema repeats 'discarded' language. However, it does not disclose return format, side effects, or how the JSON object is supplied.

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: two short statements, front-loaded with the core operation. There is no filler, and the 'Values discarded' fragment earns its place as an important behavioral clarification.

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 9 optional parameters, no output schema, and no annotations, the description is too sparse for reliable invocation. It omits the return value, which parameter to use, and why unrelated-looking parameters exist, so an agent would need additional inference to use the tool 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 the baseline is 3 and the description does not need to restate parameter details. It also does not add useful mapping between the 9 parameters and the 'JSON object' mentioned in the description, leaving ambiguity about which parameter should receive the object.

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 in a JSON object,' and adds the useful qualifier that values are discarded. This differentiates it from siblings like validate-json, though the name 'memory-key-count' makes the description somewhat redundant.

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 versus alternatives such as validate-json, search-query-len, or the other shape-check tools. The description only states what it does, not when it should be selected or when it should be avoided.

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