add

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

No annotations are provided, so the description carries the behavioral burden. For a pure arithmetic function, 'Add two numbers and return the result' fully discloses the behavior—it's deterministic, has no side effects, and returns a numeric result. While it doesn't explicitly state read-only or side-effect-free behavior, those are inherent for this simple operation, so the description is adequate.

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, front-loaded sentence with no wasted words. It states the operation and output clearly, earning every character it uses.

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 this simple, the description is complete. It states the operation, the inputs (implicitly via 'two numbers'), and the output. No output schema exists, but the return type is obvious from context. There are no missing details an agent would need to invoke it correctly.

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 already provides descriptions for both parameters ('The first number.' and 'The second number.') with 100% schema description coverage. The tool description adds no additional meaning beyond what the schema states, so the baseline of 3 applies.

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 'Add two numbers and return the result' uses a specific verb ('add') and resource (two numbers) and clearly distinguishes itself from siblings subtract, multiply, and divide. The purpose is unambiguous and action-oriented.

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 clearly implies when to use this tool (when addition is needed) and the sibling context makes the alternative tools obvious. However, it lacks explicit when-not-to-use conditions or mentions of edge cases, so it falls short of a 5.

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