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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds genuinely useful mode-dependent behavior (what changes based on the argument), but says nothing about result shape, taxonomy depth, or whether the authority list is truncated.

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?

Front-loaded with the core statement, then the two-mode behavior, then a short Args block with examples. No filler, no restatement of the tool name.

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?

Output schema exists so return values needn't be described, and annotations cover the safety profile. With one optional parameter fully explained, the only real gap is how the agent should disambiguate this tool from list_topics and top_authorities_in_domain.

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 coverage is 0% and the single parameter has no schema description at all, so the description carries the full burden — and it does: 'optional domain to drill into' plus two concrete slug examples and the null-argument behavior. Only the slug format convention itself is left implicit.

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+resource (browse the legal domain taxonomy) and enumerates its two modes: no argument returns top-level domains, a slug returns authorities in that domain. It doesn't differentiate itself from siblings like list_topics or top_authorities_in_domain, so an agent could hesitate between them.

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?

Clear context for the two call shapes — omit the argument to see the domain list, pass a slug to drill in. No exclusions or named alternatives are given, so the agent must infer which sibling to pick when it already knows a domain.

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