list_domains

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

With no annotations, the description carries the full burden, yet it discloses nothing about pagination semantics, result ordering, whether unverified/pending domains are included, or permission requirements. Only the read nature is implied by the verb 'List'.

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?

A single short sentence with no wasted words, but it is under-specified rather than efficiently concise — there is room for one clause on scope or pagination that would clearly earn 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?

For a simple paginated list tool with no output schema and fully documented parameters, the description is minimally sufficient to select the tool. It leaves open what a returned domain record contains and how pagination terminates, which an agent calling it correctly may still need.

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%, so page and per_page are already documented in the schema. The description adds no defaults, maximums, or guidance on iterating pages, so it sits at the baseline for a fully-specified 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 ('List ... domains') with a qualifier ('registered sender'), which distinguishes it from mutation siblings like add_domain or verify_domain. It does not explicitly separate it from list_mailboxes, but the resource noun does most of that work.

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?

No when-to-use guidance: nothing says whether to call this before verify_domain, how it relates to get_domain for a single lookup, or whether pagination should be iterated. The agent must infer all of this from sibling names alone.

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