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

Annotations already declare readOnlyHint, idempotentHint and closed-world scope, so the safety profile is covered. The description adds genuine behavioral context beyond that: which fields come back and that a missing domain yields an error rather than a null result.

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 sentences, zero waste: the operation and returned fields come first, the error case follows. Nothing redundant with the title or schema.

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?

No output schema exists, so the description usefully names the return fields and the error condition for a single-param lookup. Minor gaps remain (case sensitivity, whether unavailable domains are still returned with availability=false), but the essentials for correct invocation are present.

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 100% and the single 'domain' parameter carries its own description with an example ('brewjournal.com'). The tool description adds nothing further about format, case sensitivity or trailing dots, so this sits at the baseline for fully documented schema.

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 ('look up one domain in the UpSnatch catalog') and enumerates the returned fields. The 'one domain' phrasing implicitly contrasts with the search_classic sibling, but the sibling is never named, so differentiation relies on inference.

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?

Usage is only implied by 'one domain' versus a search tool in the sibling list; there is no explicit 'use this when you already have the exact domain name; use search_classic when you need to discover domains.' No prerequisites or exclusions are stated.

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