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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and a closed-world scope, so the safety profile is covered. The description contributes the useful behavioral nuance that results are 'explicit recorded' relationships (not inferred or computed), but it says nothing about empty-result behavior, data freshness, or throttling.

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?

A single front-loaded sentence with no filler; the verb and result type lead. It is efficient, though the brevity is partly what leaves usage and parameter questions unanswered.

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 no output schema, the description carries the burden of describing the return shape, and it only gestures at it ('replacement or supersession relationships'). For a 2-parameter lookup with 0% schema description coverage, the definition is minimally sufficient but does not explain how relationships are represented or how brand affects the 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?

Schema coverage is 0% and the description mentions only 'an appliance part', implicitly covering the required 'part' argument. The optional 'brand' parameter is never explained — whether it narrows the lookup, disambiguates part numbers, or is merely a filter — leaving a real gap the schema cannot fill.

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 (Return) and resource (recorded replacement/supersession relationships) scoped to appliance parts, so the agent knows this surfaces substitution data rather than a part's attributes. However, it never names or distinguishes itself from the immediate siblings lookup_part and lookup_model_parts, leaving the agent to infer the boundary.

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?

There is no when-to-use guidance: nothing tells the agent to reach for this tool when it needs to know whether a part is superseded versus using lookup_part for the part's own details. The phrase 'explicit recorded' hints that only stored relationships are returned and inference is excluded, but no alternative or exclusion is stated.

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