List units

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

Annotations already declare readOnlyHint=true, and the description is consistent with that. The description adds meaningful behavioral context by explaining that the list is empty on never-seeded instances, which is not available in the schema or annotations. This goes beyond the structured data without contradicting it.

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 two sentences with no redundant wording. The first sentence fronts the core purpose, and the second provides a relevant edge case. Every word earns its place.

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 straightforward list operation, the description provides the core behavior, an edge-case behavior, and a hint at the return content (abbreviations). Without an output schema, it would benefit from mentioning pagination or response structure, but the schema covers pagination parameters, and the tool is simple enough that this is not a critical gap.

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 75%, leaving the 'search' parameter without a description. The tool description does not mention search at all, nor does it clarify how any parameter affects results. Since the description fails to compensate for the undocumented parameter and adds no parameter-level meaning, it does not meet the baseline for high coverage.

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 begins with 'Lists the measurement units of the group, with their abbreviations,' which is a specific verb+resource combination. It clearly distinguishes list_units from sibling tools like create_unit or merge_units by focusing on the retrieval aspect. The added detail about abbreviations further clarifies the scope.

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 hints at a comparison to foods ('Like foods') to convey the empty-on-unseeded behavior, which is useful context, but it does not explicitly state when to use this tool instead of list_foods or other alternatives. There is no clear when-to-use or when-not-to-use guidance.

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