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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds the output scope—50 titles with names and current-as-of dates—but no further behavioral caveats are necessary for a zero-parameter read-only listing.

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 two tight sentences: the first states exactly what is returned, and the second gives a concrete use case with useful examples (Title 26, Title 40). No filler, no repetition, and the core information is front-loaded.

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, the description is complete. It states what is listed, what fields are included, and why the agent would call it. Although there is no output schema, the return values are described in plain language, and annotations cover behavioral expectations.

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 schema description coverage is effectively 100%, so there are no parameter semantics to document. The baseline for a zero-parameter tool is 4, and the description does not need to compensate for any schema gaps.

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 uses a specific verb, 'List', and clearly identifies the resource: the 50 Code of Federal Regulations titles with their name and current-as-of date. It also distinguishes itself from reg_cfr_section by positioning this tool as the discovery step for title numbers.

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 says this is useful for discovering title numbers before calling reg_cfr_section, which gives clear when-to-use guidance. It does not state when not to use it or mention alternatives like reg_cfr_search, but the main routing cue is present and actionable.

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