list_supported_tlds

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

No annotations are provided, so the description carries the burden. It discloses that the list is not exhaustive (via WHOIS fallback note), which is useful behavioral context about coverage limitations. However, it doesn't describe return format, ordering, or whether this reflects real-time vs cached data.

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?

Two compact sentences with zero waste. Front-loaded with the core purpose, followed by one useful caveat. Every sentence earns its place.

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 is a simple read-only list with no parameters and an output schema available. The description covers the essential purpose and a critical caveat (WHOIS fallback). An output schema exists, so return values don't need description. Slightly more behavioral context (caching, freshness) could push it higher.

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 0 parameters, so schema coverage is 100% and there are no parameters to document. The description reasonably describes what is being listed without needing to explain parameter syntax, satisfying the baseline 4 for a zero-parameter tool.

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?

Description clearly states 'List TLDs with known RDAP endpoints (IANA bootstrap + overrides)' — a specific verb (list) and specific resource (TLDs with known RDAP endpoints) with scoping detail. The mention of IANA bootstrap + overrides distinguishes scope from a generic TLD listing.

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 notes that 'TLDs missing from this list may still work via WHOIS fallback', providing important context about when this list is not exhaustive. It doesn't explicitly state when to prefer this over siblings, but the fallback caveat gives useful usage direction.

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