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

With no annotations, the description carries the full burden. It only mentions 'Values discarded,' which hints at a non-mutating operation but says nothing about side effects, permissions, return format, or failure modes. For a tool with no annotation safety net, this is severely insufficient.

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 a single concise sentence with no filler, which earns credit. However, it is under-specified to the point of being unhelpful; it does not front-load the critical information about which parameter to use or what the output is, making it more under-specification than effective conciseness.

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's simplicity, a complete description should specify the input parameter and return value. The absence of an output schema and the lack of any parameter mapping means an agent cannot correctly call this tool without additional external knowledge. The large, confusing parameter set amplifies the incompleteness.

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% with each parameter described, the descriptions are generic and unrelated to the tool's purpose (e.g., 'Git ref name; discarded after the shape check'). The tool description does not clarify which parameter is the primary input (likely 'json'), so it fails to add meaning beyond the schema and leaves the agent without direction.

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 clear verb and resource: 'Count keys in a JSON object.' However, the input schema lists 9 string parameters with no indication of which one carries the JSON object (e.g., the 'json' parameter seems relevant but is not explicitly linked). The mismatch between the stated purpose and the schema makes it ambiguous how to invoke the tool, weakening clarity.

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?

No guidance is provided on when to use this tool versus any of the 26 sibling tools, many of which are shape-checking utilities. The description offers no context for selection, leaving the agent to guess based on the name alone.

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