Sum two numbers to get their total. Use for basic addition of any numeric values.
Adds two numbers. For several operations or chained steps in one call, use batch_calc.
| Name | Required | Description | Default |
|---|---|---|---|
| firstNumber | Yes | The first addend | |
| secondNumber | Yes | The second addend |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full disclosure burden. For a pure arithmetic operation the absence of side effects is self-evident, but the description says nothing about return format, precision, or numeric limits, so it adds little behavioral context.
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?
Two short sentences with zero waste; the core operation is front-loaded before the alternative-usage note.
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 trivial two-argument pure function with a fully described schema, the description is nearly sufficient. The only gap is that no output schema exists and the description never states what is returned.
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 100% and both parameters are documented as 'the first/second addend', so the schema does the heavy lifting. The description adds no syntax, format, or constraint detail beyond what the schema already states.
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 resource with exact arity: 'Adds two numbers.' An agent can immediately tell this is a binary addition operation, not a list/aggregate or chained computation, and the description pre-empts confusion with the batch_calc sibling.
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 routes multi-step or chained work to batch_calc, which is a concrete when-to-use-else rule. However, it does not address the closely related 'sum' sibling (aggregate over a list), leaving a real ambiguity unresolved.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.