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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds nothing further: no behavior on invalid units or mismatched category, no note on precision/rounding, and no mention of cross-category errors — it merely restates the category set.

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 compact sentences with the core action front-loaded; no filler. The trailing category list is slightly redundant with the category parameter description but still serves as a quick scope scan.

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?

An output schema exists, so return values need not be explained. Still, for a conversion tool the description omits practical concerns such as unit alias behavior, case sensitivity, and what happens on incompatible or unsupported units, leaving gaps an agent would want before calling.

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 coverage is 100%, so each of the four parameters is already documented, including the alias support for from_unit/to_unit and the category enumeration. The description only repeats the category list, adding no syntax, format, or constraint detail beyond the 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?

Names a specific verb and resource ("Convert a value between units") and enumerates the supported categories, so the operation is unambiguous. However, it never distinguishes itself from overlapping siblings such as calculator_length, calculator_weight, calculator_temperature, calculator_volume_convert, or calculator_power_convert, leaving an agent unsure which converter to pick.

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 on when to use this general converter versus the many category-specific siblings (calculator_length, calculator_temperature, calculator_energy, etc.). The category list hints at scope but provides no selection logic or exclusions.

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