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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds 'performs no account actions', which reinforces the read-only nature but is redundant with annotations. It also mentions 'offer and coverage checks', which hints at the content but not at any behavioral traits like error handling or side effects. Since annotations cover safety, this is adequate but not exceptional.

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 is direct and front-loaded with the action and resource. It contains no filler and efficiently conveys the core purpose.

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?

The tool has one parameter and an output schema, which covers return values. However, the description lacks parameter semantics and usage guidance, which are important for correct invocation. While the output schema mitigates some gaps, the lack of explanation for plan_id and when to use this tool makes it only partially complete.

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?

The schema has a single parameter, plan_id, with no description coverage (0%). The description does not explain what plan_id represents or how it relates to the switching guide. Given the lack of schema descriptions, the tool description should compensate, but it fails to clarify the parameter's meaning or expected usage.

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 states a clear verb ('Read') and a specific resource ('a switching checklist with offer and coverage checks'). It distinguishes itself from siblings by focusing on a checklist with offer and coverage checks, though it does not explicitly name an alternative. It is clear enough for an agent to understand what the tool does.

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 description gives no guidance on when to use this tool versus alternatives like compare_plan_costs or get_plan_details. It does not mention any conditions, exclusions, or scenarios where this tool is preferred. The only hint is the resource type, which is not enough to route an agent reliably.

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