add

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds "Returns the sum of a and b," which is more of a restatement than new behavioral insight. No extra context about edge cases or errors is provided, but for a pure mathematical operation this is acceptable.

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 extremely concise, front-loaded with the core action, and logically structured with Args and Returns sections. Every sentence contributes meaningful information without redundancy.

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, combined with rich annotations and an output schema, covers all necessary context. The agent knows it is a safe, deterministic operation that sums two numbers and returns a number, with no missing prerequisites or side effects.

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 only lists parameters a and b with type number and no descriptions. The description adds meaning by labeling a as "The first number" and b as "The second number," which helps an agent understand the ordering and role of each argument. This compensates for the 0% schema description 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?

"Add two numbers together" is a specific verb+resource combination that clearly distinguishes this tool from siblings like subtract, multiply, and divide. The phrase states exactly what the tool does without ambiguity.

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 implies usage (when you need to sum two numbers), but it does not explicitly contrast with alternatives or state when not to use this tool. Given the sibling tools are distinct arithmetic operations, the intended use is clear, but no explicit guidance is provided.

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