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

Annotations already declare readOnly, idempotent, and closed-world, so the safety profile is covered. The description adds real context beyond them: the catalog scope (26 million part numbers), the provenance of the sources (government, OEM, commercial), a measurement date, and the two result components returned. It does not disclose behavior on malformed input or whether an invalid structure short-circuits the catalog lookup.

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 sentences, front-loaded with the action and result, with the catalog stats and provenance kept to a parenthetical. The date stamp (2026-11-03) and the exact row count are of marginal decision value for an agent, but they do not obstruct the core statement.

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?

There is no output schema, so the description must state the return values — it names both ('structural validity and catalog existence') but not their shape or fields, leaving an agent to discover that at call time. For a single-parameter, read-only validation tool this is otherwise sufficient.

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 one parameter at 100% schema coverage, the schema already carries the documented meaning. The description adds nothing about accepted part-number formats — case sensitivity, dashes/spaces, or whether wildcards are allowed — which matters for a tool with a sibling dedicated to normalization.

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 pairs a specific verb ('Validate') with a specific resource ('a part number') and adds the two things being checked: structural validity and catalog existence in PartsTable. It is clearly separable from normalize-pn and get-part by intent, though it never names those siblings 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?

The use case is strongly implied — check a part number before resolving it via get-part or search-parts — but no sentence states when to prefer this tool over those alternatives or when not to call it. No prerequisites or preconditions (e.g., 'normalize first') are given.

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