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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so safety is covered. The description adds genuinely new behavioral context: the text comparison is explicitly labeled partial and is not a legal redline, which sets the agent's expectations about fidelity of the output. It does not mention cost, latency, or size limits for large documents.

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, no filler, and the essential scope statement (what is compared, and the two input modes) is front-loaded ahead of the caveat. Every clause carries information.

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 carries the return-value burden — and it does, enumerating metadata differences, sentence-level diffs with verbatim excerpts, and the partial/not-a-redline caveat. Combined with annotations covering the safety profile, nothing an agent needs to call this correctly is missing.

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 only 50% — document_a/document_b are documented but rin and include_text are not. The description compensates by explaining that a RIN resolves to the latest proposed-and-final pair, and by implying that text diffing (and thus include_text) produces the sentence-level excerpts. It adds real meaning beyond the bare schema, though include_text's exact toggle effect is left implicit.

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 (Compare) and resource (Federal Register documents / proposed-vs-final rule for a RIN) and spells out exactly what the comparison yields: metadata differences plus sentence-level text differences with verbatim excerpts. This is clearly distinguishable from read-oriented siblings like get_regulatory_document or get_regulatory_timeline.

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?

It tells the agent the two ways to invoke it — pass two document numbers, or pass a RIN to auto-select the latest proposed and final rule. That is clear input-selection context, but it never states when this tool should be preferred over siblings such as get_regulatory_document or get_cfr_changes, so there is no explicit exclusion guidance.

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