list_agencies

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

With no annotations, the description carries the full burden. It discloses both success and error return shapes, including a retryable flag and nested child agencies. It doesn't mention performance or pagination, but for a zero-parameter listing operation this is a minor omission rather than a critical gap.

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 main purpose is front-loaded in the first sentence, followed by a compact usage scenario and a clear return format section. Every sentence earns its place; there is no filler or repetition.

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 no-parameter list tool, the description is complete: it explains the resource, the purpose, the relationship to sibling tools, and the expected success and failure payloads. Nothing an agent needs to use it 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?

The tool has zero parameters, so there are no parameter semantics to add. The description doesn't need to compensate for schema gaps, and the baseline 4 is appropriate since the dimension is trivially satisfied.

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 states a clear verb-object pair: 'List all agencies referenced in the CFR' with their title/chapter cross-references. It also differentiates itself from search siblings by framing itself as a mapping step before search_regulations/search_by_keyword.

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 explicitly says when to use the tool: to map an implied regulator to a CFR title before running search_regulations or search_by_keyword. This provides actionable context and names the relevant alternatives, even if it doesn't enumerate all non-use cases.

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