mode

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

With no annotations, the description carries the full burden of behavioral disclosure, and it does so thoroughly. It reveals that strings convertible to numbers are accepted, formatting like commas is unsupported, string/number duplicates are counted together, and the last number is returned when no repeats exist. This is excellent transparency.

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 three sentences long, with every sentence providing essential behavioral information. It is front-loaded with the primary purpose and then adds necessary edge-case details without waste.

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 empty schema and no output schema, the description covers most essential behavioral aspects: input type, string conversion, duplicates, and tie behavior. However, it does not specify behavior for an empty array or non-convertible strings, leaving minor gaps in edge-case handling.

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 is empty, so the description fully compensates by explaining that the input is an array of numbers, the conversion rules for strings, and duplicate handling. This goes well beyond the baseline 4 for zero-parameter tools.

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 uses a specific verb 'Calculates' and identifies the resource ('the mode ... from an Array of numbers'), clearly distinguishing it from sibling tools like median and average. It fully defines what the tool does in its first sentence.

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 provides clear context on when to use this tool: for calculating the mode, and it explains input constraints (strings convertible to numbers are allowed, formatting is not supported) and tie behavior. However, it does not explicitly mention alternatives or when not to use it, though the purpose is unambiguous.

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