Add a custom domain

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

Annotations only cover readOnly/destructive/openWorld/idempotent flags; the description goes well beyond by disclosing the confirm-gated preview, the plan restriction, the 5-domain cap, and the exact DNS records the caller must add afterward. That is exactly the operational context an agent needs before mutating state.

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-loads the 'Write.' marker and the core action, then layers constraints. The single dense paragraph is information-rich but slightly packed; a reader must parse several clauses to find the preview behavior.

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, and the description compensates by describing the returned DNS records and preview payload. Combined with the plan/limit/confirm disclosures, nothing essential for correct invocation is missing.

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 baseline is 3; the description adds value by explaining what the preview returns (plan, limit, domains already added) and reinforcing that confirm:true is the switch between no-op and write. Hostname semantics are largely already in the 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?

Names a specific verb and resource ('Adds a custom link domain') and even disambiguates what it returns (CNAME + two TXT records). It is clearly distinct from siblings like list_domains and remove_domain.

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?

Gives concrete gating conditions: 'Scale and Enterprise only, at most 5 per workspace', and explains that without confirm:true it becomes a preview. It doesn't explicitly route to sibling tools (e.g. list_domains for existing domains), but the when-to-use context is unambiguous.

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