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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered without the description. The description does add that it returns kind, components, and short ID, but is silent on what happens when a URN fails validation — an error versus a negative result is ambiguous, which matters for a validation tool.

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 short sentence that front-loads the action and immediately states the return payload; no filler or redundant restatement of the title.

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, and the description compensates by naming the three returned fields, which is adequate for a single-argument parser. The remaining gap is failure behavior and the shape of 'components', which an agent would want to know before relying on 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?

The single parameter has 100% schema coverage including a concrete URN example, so the schema carries the semantics. The description adds nothing about URN structure or what 'components' means beyond the schema's example, which is a baseline 3.

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 ('FactLot URN') and names the payload it returns (kind, components, short ID). It does not, however, distinguish this from nearby siblings such as id_parcel, id_entity, id_space, or fact_validate, so an agent must infer which identifier family this handles.

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 by the phrase 'FactLot URN' — an agent can guess this is the parser for FactLot identifiers, but there is no explicit when-to-use, no when-not-to-use, and no pointer to id_parcel/id_entity or fact_validate as alternatives.

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