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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so safety is covered. The description adds non-obvious behavioral content: the result set includes stale/frozen routes left behind after handover, which an agent would not infer from the schema or annotations and which matters when deciding to disable or replace paths.

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 filler: what is returned first, when to call it second. The most decision-relevant detail (frozen routes) is front-loaded rather than buried.

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?

Annotation coverage, a 100%-described single param, and no output schema leave little unsaid; the description covers trigger and result scope. It could still mention whether the domain must be verified/active before listing, and roughly what a route entry contains, but nothing critical is missing for correct invocation.

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?

With a single required parameter and 100% schema coverage, the schema already documents domainId and even points to get_domain_status and activate_domain_handover as sources. The description adds no additional syntax, format, or constraint information beyond that, so the baseline 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?

States a specific verb+resource (list routes under a custom domain) and immediately scopes it further by noting it includes frozen continuity routes left after handover. That detail separates it cleanly from the mutating siblings disable_domain_route and enable_domain_route, which operate on the same resource.

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?

"Use after activate_domain_handover when the user wants to inspect, disable, or replace existing paths" gives a clear triggering context and hints at the follow-on tools. It stops short of naming when not to use it (e.g. a domain without handover), so it is strong but not fully exhaustive.

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