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

Goes well beyond annotations (readOnly=false, idempotent=true, destructive=false): it discloses immediate effect with a few-minute propagation window, that the domain keeps serving during propagation, that unfiled domestic/global calls are refused with a reason (and why syncing lags), the permission requirement (workspace owner), and a confirm-with-user norm.

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?

Opening sentence states the action, then the filing/propagation constraints follow in a logical order. The second and third sentences are dense run-ons with semicolons and parentheticals that slow parsing, though no sentence is pure filler.

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 3-param mutation with no output schema, it covers propagation timing, failure mode, permissions, and confirmation intent — enough to call correctly. It does not mention what the tool returns or how a refusal is surfaced to the caller.

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%, and the enum description already explains domestic/global/overseas including filing requirements; the description largely restates this. It adds the practical consequence ('region=overseas needs no filing') but says nothing extra about hostname vs domain_id selection.

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: 'Change the region a custom domain is served from on the acceleration network.' This clearly separates it from bind_domain/unbind_domain/verify_domain and from the routing-related set_domain_route without needing the schema.

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 explicit when-to-use and when-not conditions: a domain without an ICP filing is auto-served overseas, and this tool is for after filing to set domestic or global; overseas needs no filing; workspace owner only; confirm with the user first. It does not name sibling tools as alternatives, so it falls short of a 5.

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