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

With no annotations provided, the description carries the behavioral burden. 'Values discarded' is a genuine disclosure that the values are ignored, which is helpful. However, it does not state the return format, handling of invalid JSON, depth of counting, or whether the operation is side-effect free.

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 and front-loaded. Two short sentences state the core action and the key behavioral trait with no filler or repetition.

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 no annotations and no output schema, the definition is incomplete. The nine-parameter schema with unrelated-looking fields makes it especially important to state which input to provide and what the count applies to; the description does not do that.

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. The description adds little parameter-specific meaning: it does not map 'JSON object' to the 'json' field or clarify how the nine optional string parameters relate to the count. The 'values discarded' hint is useful but not enough to resolve the ambiguity.

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 concrete action—'Count keys in a JSON object'—and adds a useful qualifier, 'Values discarded,' which distinguishes counting from validation or value-based tools. It is not vague, though it does not specify whether top-level or nested keys are counted or which schema parameter is 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 guidance about when to use this tool versus siblings like validate-json, and no mention of exclusions or alternatives. The agent must infer entirely from the name and terse description that this tool is for key counting rather than validation.

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