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

Annotations already cover readOnly/idempotent/non-destructive, and the description adds real value beyond them: abbreviation tolerance, the KiB-vs-KB and bits-vs-bytes distinction, and the US-vs-imperial disambiguation rule. It does not say how incompatible or ambiguous units (e.g., mass to length) are handled, which is the one behavioral gap.

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 dense sentences, front-loaded with scope and followed by the two conventions an agent would otherwise get wrong (abbreviations, US default). No filler.

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 3-parameter tool with full schema coverage and no output schema, the description covers scope and the two realistic ambiguity traps. Missing only error/edge-case behavior for dimensionally incompatible conversions.

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 100% and the schema already gives example values for from/to, so the baseline is 3. The description's unit-family list and abbreviation examples add marginal orientation but no format or syntax rules 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?

States a specific verb (Converts) and resource (a value between units), then enumerates the supported unit families, which cleanly separates it from siblings like convert_timezone and calculate.

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?

Gives clear context for use: accepted abbreviations are listed and the default US-customary convention for cup/pint/quart/gallon is stated with an explicit override ("unless you say imperial"). No alternative tool exists for this job, so no exclusion clause is needed.

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