Grams ↔ meters ↔ yards

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

Annotations already cover the safety profile (readOnly, idempotent, openWorld), and the description adds the important accuracy caveat that weight-only conversion is an estimate. It does not, however, describe behavior on conflicting inputs or how the direction of conversion is chosen.

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?

Three sentences, front-loaded with the verb and scope, examples do real work. The closing sentence about yarn being sold by weight is motivational framing rather than operational information, costing it the top score.

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 no explanation, but the critical ambiguity for a 5-parameter conversion tool — which combination of grams/yards/meters to supply and what happens if several are given — is left unresolved.

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 schema description coverage at 20%, the description must carry more: it names yarn_id and weight's role but never states that grams/yards/meters are alternative inputs, whether they are mutually exclusive, or how the enum weight values map to ratios. It partially compensates, so a baseline 3.

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 (yarn amount) with the exact unit spaces involved (grams, meters/yards, skeins), plus concrete example phrasings. It is clearly distinguishable from siblings like yarn_needed or adjust_for_gauge.

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?

Explicitly says to pass yarn_id when the exact yarn is known and to fall back to a weight-based typical ratio otherwise — a real routing rule between two parameters. It stops short of naming a sibling alternative or a when-not-to-use case, so not a 5.

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