list_agencies

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

Annotations already mark the tool as readOnly and non-destructive; the description goes well beyond this by explaining that summary_only strips children and most cfr_references, merges child-owned references into the parent row, and changes payload size from ~100 KB to ~20 KB. The DFARS example clarifies a subtle consequence of that merging, which is exactly the kind of behavioral nuance an agent needs.

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 five sentences with the core action and return information first, followed by a concrete use case and then parameter details. Each sentence adds distinct value with no filler.

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?

The tool has an output schema and only one optional boolean parameter; the description covers the tool's purpose, return fields, the summary mode's data implications, and how to opt out. Nothing needed to invoke 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 schema only gives the parameter a title and default, with no descriptive text. The description fully explains summary_only: it strips children and most cfr_references, merges child-owned references into the parent row, and setting False returns the full raw payload. This thoroughly compensates for the 0% schema description coverage.

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 ('List'), a clear resource ('all agencies'), and a scope ('with their CFR title and chapter references'), more specific than the tool name alone. It further states the return fields (agency names, slugs, CFR titles/chapters), making it easy to distinguish from siblings like get_cfr_content or list_sections_in_part.

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 line 'Useful for finding which chapter corresponds to an agency's FAR supplement' gives a concrete scenario for selecting this tool, which is clear usage guidance. It does not explicitly name alternative tools or say when not to use it, so it stops short of a 5.

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