is_prime

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

No annotations are provided, so the description carries full burden. It only states the basic function without disclosing behavior of the 'rigorous' parameter, performance characteristics, or edge cases like negative numbers or large inputs. The agent gets minimal insight into how the tool operates.

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 short sentence, which is concise and front-loaded. However, it sacrifices necessary detail for brevity, making it under-specified rather than efficiently informative. Still, there is no wasted text.

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 an output schema exists (though not detailed), the description doesn't need to explain return values. However, it fails to explain how to use parameters effectively, and the presence of sibling tools is not leveraged to provide usage context. The tool is simple but still incomplete without parameter semantics.

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?

The input schema has two parameters with no descriptions (0% schema coverage). The description adds no meaning beyond parameter names. The 'rigorous' boolean parameter is not explained, leaving the agent unsure of its effect. This is a significant gap.

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 clearly states the tool's purpose: testing if an integer is prime. It uses a specific verb and resource, making the function immediately understandable. However, it does not differentiate from sibling tools like 'factor_int' or 'primes_range', which are also prime-related.

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?

The description provides no guidance on when to use this tool versus alternatives. For instance, it doesn't mention that this tool is for single number checks while 'primes_range' handles ranges. Without such context, an agent might choose the wrong tool.

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