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

This is an annotation contradiction. The description states an open-world interpretation—'Absence means the sources did not state a value — never that the part lacks the property'—while the annotations set openWorldHint=false. The readOnlyHint and idempotentHint are supported, but the open-world contradiction makes the behavioral disclosure misleading.

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 sentences, front-loaded with the primary action, and the second sentence adds a critical semantic caveat. There is no filler, and every word earns its place.

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?

Although an output schema exists and the purpose is clear, the description lacks usage differentiation from check_compatibility and, more critically, directly contradicts the openWorldHint annotation. An agent cannot confidently rely on the absence semantics described, making the overall description incomplete for safe and correct tool selection.

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?

The input schema has 100% coverage of all three parameters, so the schema already carries parameter semantics. The description adds no parameter-level detail beyond reinforcing that 'two catalogue parts' map to the a and b parameters, which is the baseline expected for full schema coverage.

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 uses the specific verb 'compare' with a clear resource ('two catalogue parts') and scopes it as an 'aligned attribute-by-attribute comparison,' which distinguishes it from sibling tools like check_compatibility and get_part. This makes the tool's core purpose immediately clear.

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?

No when-to-use guidance or exclusions are provided. The description never contrasts compare_parts with check_compatibility, get_part, or search_parts, leaving an agent to infer when this tool should be preferred over siblings.

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