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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions that values are discarded, which is a useful trait, but it does not explain the input format, how the JSON is provided, what happens with the other eight parameters, or what the output looks like. It also fails to clarify that the 'json' parameter is the relevant one, and the schema descriptions for other parameters suggest they are all discarded, creating ambiguity about the tool's actual behavior.

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 sentences with no wasted words. It states the core action and a key behavioral note (values discarded) without fluff. The information is front-loaded and easy to parse, making it efficient for an agent to scan.

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 has nine parameters, none required, and no output schema, the description is far from complete. It does not specify the input format (e.g., that the JSON should be passed via the 'json' parameter), the expected output (e.g., an integer count), or any edge cases or error conditions. The description leaves too much unspecified for an agent to call the tool correctly without additional context.

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 the schema has 100% description coverage, the tool description adds no meaning beyond what the schema already provides. It does not indicate which of the nine parameters should be used to supply the JSON object, nor does it clarify the role of the other parameters. The description's mention of 'JSON object' does not map explicitly to the 'json' parameter, leaving the agent to guess. The description fails to compensate for the high parameter count and the fact that most are irrelevant to the core operation.

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: counting keys in a JSON object, with the caveat that values are discarded. This is a clear verb+resource pair and distinguishes the tool from siblings like validate-json or fetch-status, though it does not explicitly name alternatives. The purpose is unambiguous enough for an agent to understand what the tool does, though it could be clearer about the input parameter.

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. It does not mention any preconditions, exclusions, or context in which it should be preferred. The agent is left to infer that it is used when counting JSON keys is needed, but no explicit direction or comparison with sibling tools is provided.

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