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

With no annotations, the description must disclose behavior, and it does state the core operation and return value. It does not mention edge cases, type coercion, or pure-function guarantees, but for a basic arithmetic tool this is minimally adequate.

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 one short, direct sentence that conveys the function and result with zero wasted words. It is as concise as possible while remaining informative.

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 an extremely simple tool with two numeric parameters and no output schema, the description covers everything an agent needs to call it correctly. No additional context like side effects, permissions, or pagination is relevant here.

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?

Schema description coverage is 0%, so the description must compensate. It only says 'two numbers,' which broadly describes both parameters but does not individually explain a and b, their roles, or any ordering semantics. The parameter names are generic, so more detail would help.

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 action ('adds'), the operands ('two numbers'), and the result ('returns the sum'). It clearly distinguishes itself from siblings 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?

Usage is implied by the simple arithmetic purpose: use when a sum of two numeric values is needed. However, there is no explicit guidance about when not to use it or why it might be preferable to alternatives, though the siblings are unrelated functions.

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