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

No annotations are provided, so the description bears the full burden of behavioral disclosure. It clearly indicates that the tool performs a pure arithmetic addition and returns a single numeric result. For a deterministic function with no side effects, this level of transparency is adequate; it does not mention edge cases or precision issues, but these are not critical for a basic 'add' operation.

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, well-formed sentence with no redundancy. Every word earns its place, and the core information is front-loaded. It is appropriately sized for the tool's trivial complexity.

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, the description is fully complete. It covers the operation, the parameters, and the return value. No output schema is needed because the return type is obvious. There is no additional context, such as side effects or external dependencies, that an agent would need to know to call this tool 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 schema provides no descriptions for parameters (0% coverage), so the description must compensate. It does so by stating 'Adds two numbers,' which directly ties the parameters a and b to the operands of the addition. The names themselves are self-explanatory, and the description reinforces their role, adding meaning beyond the bare type declarations.

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 specific verb ('Adds') and resource ('two numbers') and clearly indicates the result ('returns the sum'). This is immediately distinguishable from sibling tools echo and server_time, which serve entirely different purposes.

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?

While the description does not explicitly name alternatives or exclusions, the purpose is self-evident: it is the tool to use when one needs to compute the sum of two numbers. Given the simplicity of the operation and the obviously unrelated siblings, this implicit guidance is sufficient, though a brief mention of when not to use it would be more explicit.

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