compare_dimensions

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavior beyond those: 'Unknowns yield hold' and 'Does not establish physical fit or source truth,' plus the requirement for exact decimal conversion. This does not contradict any annotation.

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 dense sentences with no filler. The main verb and object are front-loaded, followed by a compact list of required fields and constraints, and it ends with a pointer to examples. Every phrase contributes information.

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?

The schema defines no output schema, and the description only hints at result behavior with 'Unknowns yield hold,' without stating the full set of outcomes (e.g., match/no-match) or the response shape. It does not explain how toleranceMm affects the comparison or what evidenceRef is for. The 'See examples/dimensions.json' pointer helps, but the description itself leaves an agent with incomplete expectations for the tool's result.

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 0% schema description coverage, the description is the only semantic source for parameters. It compensates by defining the axis shape as {value: decimal string, unit: mm/cm/m/in}, requiring toleranceMm as an explicit decimal string, and naming schemaVersion, source/candidate fields. It leaves some semantics implicit (e.g., what basis product/package means, how toleranceMm is applied) but covers the critical format constraints.

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 starts with a specific verb and resource: 'Compare supplied length, width and height using exact decimal unit conversion.' It also names unique input requirements (schemaVersion, source/candidate, itemId, basis, evidenceRef) that differentiate it from siblings like compare_feed_snapshots and review_product_record. This makes the tool's purpose unambiguous.

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 provides clear input prerequisites ('Input requires schemaVersion 1.0, source and candidate...') and constraints ('Same item, basis and named axes required'), which tell an agent when the tool is applicable. It also gives negative guidance: 'Does not establish physical fit or source truth,' preventing misuse. However, it never explicitly contrasts with sibling tools, so an agent must infer the alternative from the purpose statement.

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