add

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

The description is consistent with the annotations: readOnlyHint=true and openWorldHint=false match a pure, side-effect-free computation. However, it adds nothing beyond what the annotations already imply — no statement about the return type (number vs. string) or handling of edge inputs like very large or non-finite values.

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?

A single sentence with zero waste, front-loading the only information needed. Proportional to the complexity of the tool.

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?

With annotations covering the safety profile and no output schema, the definition is workable, but the caller is never told what comes back (a number, a formatted string?) for a tool whose entire value is its return value. That single omission is the main completeness gap.

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 carry the load; 'two numbers' confirms both parameters are numeric operands, which is the only semantics these trivially named params ('a', 'b') require. It adds no ordering or range meaning, but little is genuinely missing.

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?

States a specific verb and the exact operation ('Add two numbers'), which is unambiguous even though the tool name 'add' alone is generic. It does not need to differentiate from the only sibling (word_stats), which operates on an entirely different domain.

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?

No guidance on when to use this versus alternatives, nor any stated preconditions. For a trivial arithmetic tool the omission is low-cost, but the description still leaves usage entirely to inference from the name.

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