add

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

With no annotations, the description carries the full burden of behavioral disclosure. It fully describes the behavior: adds two numbers and returns their sum. There are no side effects, prerequisites, or hidden behaviors. The output schema handles return values.

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, clear sentence with no unnecessary words. It is appropriately sized for the tool's simplicity and is front-loaded with the operation.

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—two numeric parameters, an output schema, and no annotations—the description is fully complete. It clearly states what the tool does, with the schema documenting inputs and outputs.

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 describes both parameters (a and b) with 100% coverage ('First number' and 'Second number'). The tool description adds no additional meaning beyond the schema, only restating the operation. This matches the baseline for full schema coverage.

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 together' uses a specific verb and resource, clearly distinguishing it from sibling tools like subtract, multiply, and divide. It leaves no ambiguity about the operation performed.

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 states the operation (adding two numbers) and implicitly indicates when to use it—whenever addition is needed. It lacks explicit mention of alternatives, but for such a fundamental operation, the context is sufficiently clear.

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