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

No annotations are provided, so the description carries the full burden of disclosing side effects and behavior. It does say values are discarded, which is useful, but it does not state whether the operation is purely read-only, what happens for invalid JSON, or what output the caller should expect. For a tool with no annotations and no output schema, this is minimal disclosure.

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 two short sentences, directly states the main behavior first, and contains no filler or redundancy. Every word earns its place.

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?

A 9-parameter tool with no required parameters, no output schema, and no annotations needs much more context than 'Count keys in a JSON object.' The description does not explain which parameter to supply, what the result format is, or what happens for edge cases such as missing JSON or invalid input.

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 parameter descriptions themselves are documented. However, the tool description does not map the 'JSON object' to the json parameter, and with 9 optional unrelated parameters the agent must infer which to pass. The schema helps, but the description adds little semantic guidance beyond it.

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 says exactly what the tool does: count keys in a JSON object and discard values. This is a specific verb and resource, and it distinguishes the tool from siblings like validate-json or yaml-ok. What it does not do is identify which of the 9 input fields supplies the JSON object.

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 when-to-use guidance, no exclusions, and no mention of alternatives. The description does not say whether this should be used over validate-json, yaml-ok, or other shape-checking siblings, leaving the agent to infer the appropriate selection context.

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