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

With no annotations, the description carries the full burden and does state the core behavior: addition and returning a sum. It does not address edge cases or output shape, but for a pure arithmetic operation the main behavior is transparent.

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 eight-word sentence with no filler. The action and result are immediately front-loaded.

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 two-operand arithmetic tool, the description plus input schema cover what to pass and what to expect. It omits explicit return format and error behavior, but the simplicity of the operation makes those omissions minor.

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 has no per-parameter descriptions, and the description only says 'two numbers' without naming a and b or adding constraints. However, addition is commutative, so the missing role differentiation is not a practical issue.

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 phrase 'Adds two numbers and returns the sum' uses a specific verb and outcome. It clearly identifies the operation and is easily distinguishable from echo and server_time.

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?

There is no explicit when-to-use or alternatives statement. The intended use is implied by the description and tool name, but selection guidance is left to obviousness rather than being stated.

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