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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, fully covering the safety profile for a pure calculation. The description adds only 'Returns converted density,' which is minimal. There is little behavior left to disclose, so a 3 is appropriate, but nothing beyond the annotations is meaningfully added.

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?

Compact and front-loaded: the conversion statement comes first, followed by usage context and inputs. The 'Inputs: value, from-unit, to-unit' sentence largely duplicates the schema, which is minor padding, but the whole text is short and readable.

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?

With an output schema present, return-value explanation is unnecessary, and annotations cover safety, so the remaining burden is light. Still, the description gives no guidance on choosing this over calculate_density or convert_weight and lists units inconsistent with the enum, leaving gaps an agent must resolve from the schema.

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 enum values are self-documenting, so the schema carries the load (baseline 3). The description merely restates the three input names, and its unit list (lb/gal) contradicts the actual enum (oz_in3), adding a small risk of confusion rather than value.

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 (Convert) and resource (density) with an explicit scope of units, so it is clearly distinguished from generic siblings like convert_weight. However, the listed units do not match the schema enum (it claims lb/gal while the schema offers oz_in3), and it does not differentiate itself from calculate_density, which likely computes density rather than converting it.

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 domain hints ('engineering, chemistry, fluid mechanics') indicate context but not when to choose this tool over calculate_density or convert_* siblings. The 'See list_bundles' pointer is a discovery aid, not an alternative-selection rule. No prerequisites or exclusions are stated.

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