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

With no annotations, the description must carry the behavioral burden. It discloses the ownership requirement and the downstream impact on URLs and emails, but it does not mention side effects on the previous primary domain, prerequisites like domain being attached, or whether the operation is reversible.

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?

The description is a single sentence that front-loads the action and consequence, then adds the ownership restriction. Every clause earns its place, with no filler or redundant restating 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?

For a simple two-parameter mutation with a fully covered schema, the description supplies the key missing context: the access restriction, the domain's role, and the practical effect. It could add a note about prerequisites or previous-primary behavior, but the agent has enough to select and invoke the tool correctly.

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%, with the schema already defining 'domain' as 'A domain the workspace answers on' and 'workspace' with usage context. The description adds no further parameter-level meaning, so the baseline 3 applies.

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?

The description uses a specific verb and resource ('Make one of the workspace's domains the primary one') and explains the practical effect (URLs and emails use it). It clearly distinguishes this from domain_attach/domain_detach, but it doesn't explicitly name or contrast an alternative sibling like domain_repoint.

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 phrase 'Owners only' gives an important authorization constraint, and the effect on URLs/emails implies when the tool matters. However, it does not explicitly state when to prefer this over sibling tools such as domain_attach or domain_point, nor does it give any 'when not to use' guidance.

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