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

Goes well beyond the annotations by disclosing error semantics (a month or region not on file returns not_found), auth and cost ('free, no sign-in required'), and a concrete rate limit ('20 calls per minute per IP, then rate_limited'), plus the data source and a legal disclaimer. The annotations already carry the read-only/closed-world profile, so this is a genuinely additive disclosure; the only missing piece is whether the cutoff is a rank number versus a date field, which the output schema presumably covers.

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?

Five short sentences, front-loaded with the core behavior, then the routing to siblings, then failure mode, then operational facts. Every sentence carries distinct information; none repeats the schema or annotations.

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?

With an output schema present, return values need no explanation, and the description still covers failure modes, rate limits, cost, and data provenance. The only gap is that it does not say whether a missing country exception falls back silently or is flagged, though the schema hints at the fallback.

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?

Schema description coverage is 100%, so month format, the exact region list, and the country fallback behavior are already documented in the schema. The description's phrase about a 'country exception the bulletin lists within that region' reinforces the country parameter's semantics but adds little beyond what the schema states. Baseline 3 is appropriate.

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?

States a specific verb and resource: returns the Diversity Visa rank cutoff for one region in a given month's bulletin, plus any country exception listed within that region. This is clearly separable from get_visa_bulletin (family/employment chart dates) and get_visa_bulletin_notes (advisory notes) without opening either schema.

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?

Gives the triggering scenario explicitly ('use it when a DV selectee asks whether their case number is current') and names both alternatives with the conditions that select them. Nothing is left to inference about when this is the wrong tool.

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