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

The readOnlyHint and destructiveHint already signal a safe read, and the description adds meaningful behavioral detail: it returns only published final rules, sorts by soonest effective date, includes a verbatim quote, and matches the part whole so "40 CFR 5" never pulls in 40 CFR 52-related rules. This goes beyond what annotations alone provide.

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?

Three tight sentences move from user intent to input format to output behavior and edge-case matching. No filler or repetition of schema details; every sentence earns its place.

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 read-only listing tool with an output schema, the description covers what an agent needs to invoke it correctly: how to ask the question, what input is required, what ordering and content to expect, and how matching is scoped. No significant gap remains.

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 schema already documents all three parameters at 100% coverage, and the description reinforces cfr_part with examples, the refusal rule for bare numbers, and the exact-match semantics. It adds context beyond the schema without needing to restate from/limit.

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 names a specific action and resource: get already-published final rules that amend a given CFR part. It also states the output ordering, the DATES paragraph, and the whole-part matching behavior, making the tool's scope unmistakable even before considering siblings.

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 description gives concrete input examples ("49 CFR 192"), states the sort order, and warns that bare part numbers are refused. It does not explicitly contrast with list_rules_taking_effect or other siblings, but the amendment-focused wording makes the intended use clear.

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