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

With no annotations provided, the description carries the transparency burden. It discloses 'FREE' (no cost), 'Deterministic' (pure function, no side effects), and the 400 error response for invalid conversions. These are meaningful behavioral traits beyond what schema alone would convey.

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 compact: two informative sentences plus two clarifying examples. Every sentence contributes to the agent's understanding, with no filler or redundant restating of the schema.

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 tool's simplicity and the rich schema coverage, the description adequately covers purpose, parameter semantics, examples, and error behavior. It stops short of specifying the exact return value shape, but for a straightforward converter the output is highly inferable.

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 descriptions cover all three parameters (value, from, to), providing a baseline of 3. The description adds semantic value with concrete examples like {value:100, from:'c', to:'f'} and unit abbreviations ('GiB', 'MB'), clarifying accepted formats that the schema does not fully illustrate.

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 opens with a specific verb and resource: 'Convert a value between units in the same dimension' and enumerates a clear list of dimensions (length, mass, temperature, etc.). This directly distinguishes it from sibling tools like currency and timezone, which handle different conversion types.

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 tool explicitly limits usage to same-dimension conversions and states 'Different-dimension conversions 400', effectively signaling when not to use it. It does not explicitly point to alternative tools by name, but the boundary is clearly communicated.

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