add_numbers

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

No annotations, but description details return format (rounded to 2 decimal places) and supports negative numbers for subtraction. Sufficiently transparent for a simple addition tool.

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?

Concise with clear Args and Returns sections. Every sentence is useful, no fluff.

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?

Given the simple input schema and output schema mentioned, the description fully covers behavior, parameter usage, and return format. Complete for the tool's purpose.

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 coverage is 0%, but description explains the numbers parameter as 'List of numbers to add together' and mentions negative values for subtraction, adding value beyond the schema.

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 clearly states 'Helper tool for adding numbers together' and provides concrete use cases like summing expenses and totals, distinguishing it from unrelated sibling tools.

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?

Explicitly recommends using this tool for arithmetic operations to avoid errors, with examples. Does not explicitly state when not to use, but context makes it clear it's for arithmetic only.

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