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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds a genuinely non-obvious behavioral fact — the call must be authenticated with a plan bearer token and will fail with an x402 token — which is valuable context beyond the annotations. It says nothing, however, about scoping (all hosts vs. plan-scoped subset) or what happens when the plan has no watched hosts.

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 short fragments with no filler, and the auth constraint is front-loaded. The terseness tips into under-specification, though: "Hosts on this alerts plan" is not a complete clause and reads like a note rather than an instruction.

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?

This is a simple single-parameter read tool with no output schema, so it does not need extensive documentation, and the auth requirement is the most important thing to convey — which it does. Still missing is any statement of what the call returns (a list of host entries?) and whether results are plan-scoped or global, which an agent needs to chain into follow-up calls.

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 0% for the single "token" parameter, so the description carries the explanatory burden, and it does clarify the token's type (plan bearer token, not x402). That is meaningful beyond the schema, which merely says the param is a string. It does not clarify whether the token is required, how it is transmitted, or what a missing token means (required_parameters is 0).

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?

"Hosts on this alerts plan" is a fragment with no verb; the agent must combine it with the tool name (watch_list) and title ("List watched hosts") to infer that this returns the watched-host set for the alerts plan. The resource is identifiable, but the description alone never states the action, and nothing distinguishes it from watch_add/watch_remove.

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 only directive is an authentication constraint ("Plan bearer token, never x402"), which is about how to call the tool rather than when to select it. There is no guidance on when to use this versus watch_add, watch_remove, or other list-style siblings, and no stated prerequisites or exclusions beyond the token type.

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