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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuine domain semantics not present in any structured field: a part belongs to exactly one style, and pieces attached to that style apply to every part in the style, which tells the agent how to interpret the returned pieces.

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?

Two short sentences with the core action front-loaded and no filler. The second sentence earns its place by explaining style/piece inheritance, though it sits slightly apart from the operational description.

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 full annotation coverage and no output schema, the description says what is fetched and what is bundled into the response. Remaining gaps (behavior on a nonexistent ID, whether pieces are nested or referenced) are minor for this complexity level.

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 0% for the single partId parameter, the description must carry the meaning, and it only confirms that the value is a part ID. It adds no detail about ID format, valid range, or lookup behavior beyond the schema's integer/exclusiveMinimum constraint.

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?

"Get a part by ID" states a specific verb and resource, and adds that the response includes pieces and style. That distinguishes it from list_parts and implies a single-record fetch, though it never names the sibling alternatives 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 only implied: the phrase "by ID" suggests this is for when you already know the identifier, but nothing says when to prefer list_parts to discover IDs or how this differs from get_part_class. No exclusions or prerequisites are stated.

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