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

Annotations already provide readOnly, idempotent, and non-destructive hints. The description adds the 'Keyless' behavioral trait, indicating no authentication key is needed, and provides concrete examples of the listing content (title 18 and title 26). This goes beyond what annotations convey.

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?

The description is remarkably brief: one functional sentence, concrete examples, a two-word keyless note, and an explicit usage instruction. Every sentence earns its place and the key usage guidance is front-loaded near the end but still prominent.

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 zero-parameter, read-only listing tool, this description fully covers what the tool returns (54 titles with subject names), provides examples, notes keyless access, and explains when to use it ahead of usc_section. No output schema exists, but the return shape is adequately implied.

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 tool has zero parameters and an empty input schema, so the baseline is 4. The description's 'Keyless' statement confirms no input or key is required, which is the only relevant parameter-level guidance needed here.

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 opens with a specific verb and resource: 'List the 54 titles of the United States Code with their subject names.' It also distinguishes the tool from usc_section by framing it as the step to use when you know a subject area but not the governing title.

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 explicitly instructs when to use it: 'Use when you know the subject area but not which title governs it, before calling usc_section.' This gives both a trigger condition and an indication of how it fits among sibling tools.

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