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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile and the absence of external side effects are covered. The description's genuine addition is the return content, notably that prices are dated and carry sources and that compliance data (NDAA/Blue UAS/FCC) is included, but it says nothing about behavior on an unknown id or result size.

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?

One dense, front-loaded clause that opens with the scope ('Full record for one part') and then lists payload categories in decreasing order of usefulness. Every item listed carries information an agent would use for selection.

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 single-parameter read tool with annotations covering safety and no output schema, the description is close to sufficient: it explains what comes back, which substitutes for the missing output schema. The remaining gap is error/empty behavior, which is minor at this complexity.

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 single id parameter is fully documented in the schema ('Maglev part id, e.g. from search_parts'), and the description adds no format, sourcing, or lookup guidance beyond it. With 100% schema coverage, baseline 3 is the correct ceiling here.

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 retrieval verb and resource ('Full record for one part') and enumerates the payload (specs, dated prices with sources, maker, HTS, compliance flags, equivalents). The 'full record' framing implicitly contrasts with the summary-style search_parts, though no sibling is named explicitly.

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?

Usage is implied rather than stated: 'Full record' plus the enumerated detail tells an agent this is the detail-fetch step after search_parts. There is no explicit when-to-use, when-not-to-use, or named alternative (e.g. compare_parts, find_equivalents) despite several siblings that could compete for the same intent.

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