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

Annotations already declare the tool read-only, idempotent, and non-destructive. The description adds useful behavior beyond that: exact conversion tables, a list-all mode when 'to' is omitted, and a binary data-size convention. This gives the agent a clear model of what the tool does without contradicting the annotations.

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 front-loaded with the main behavior before moving to examples and details. It avoids repeating the schema except for the beneficial 'omit to get every compatible unit' hint, though the trailing 'Price: free' and ellipsis are minor additions.

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 read-only converter with no output schema, the description gives the necessary unit vocabulary, the list behavior, exactness, and binary sizing. It stops short of describing response shape or error handling for unsupported units, but those are less critical given the tool's simplicity.

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?

With only 33% schema description coverage, the description compensates by listing concrete accepted abbreviations for from/to and clarifying binary units. It does not map every abbreviation to its dimension, but it provides enough value to meaningfully supplement the sparse 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 uses a clear verb and resource: it converts between named unit categories and can list all convertible units. The category list is specific, though the trailing 'and more' leaves scope slightly open and the description does not explicitly separate it from the sibling time_convert.

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?

There is no guidance about when to use this tool instead of related siblings like time_convert, price, or fx_rates. The description covers time units among many categories but never states exclusions or when the specialized sibling tools should be preferred.

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