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

No annotations are provided, so the description carries the full burden. It explicitly states the tool returns the sum, indicating a pure function with no side effects. It does not mention edge cases like overflow or handling of non-numbers, but for a basic arithmetic operation this is reasonable.

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, tightly worded sentence with no filler. It front-loads the verb and immediately states the result, making it easy to parse quickly.

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 that simply takes two numbers and returns a sum, the description is fully sufficient. There is no output schema, no nested objects, and no complex parameters, so nothing more is needed for an agent 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 has zero description coverage for the parameters, so the description must supply meaning. 'Adds two numbers' clearly indicates that both a and b are the operands, adding semantic value beyond the raw type 'number'. This fully clarifies the purpose of each parameter.

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 operation: adds two numbers and returns the sum. This clearly distinguishes it from sibling tools like echo and server_time, which serve entirely different purposes. The verb and resource are explicit.

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 the tool is for arithmetic addition but does not explicitly contrast with sibling tools or provide conditions for when to use this tool versus alternatives. However, given the simplicity and the obvious difference from echo/server_time, the intended use is clear.

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