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

No annotations are provided, so the description carries the full burden. It clearly communicates that this is a non-binding, display-only quote, that authentication is required, and that the backend re-derives the authoritative price at purchase. It does not describe the response shape or error behavior, but the essential behavioral caveats are present.

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?

Three compact sentences front-load the purpose, then state required and optional inputs, and end with an important caveat about price authority. There is no filler, no tautology, and no unnecessary repetition of the tool name.

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 read-only quote tool with only three parameters and no output schema, the description covers the necessary input sourcing, term choices, authentication, and the non-authoritative nature of the quote. It does not specify the return shape, but that is a minor gap given the simplicity of the operation and the absence of an output schema.

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 only 33%, but the description compensates well: it explains that packageId comes from listMailPlans and that term accepts MONTHLY or ANNUAL with a default. Combined with the schema's description of sessionKey, all parameters have meaningful guidance.

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 specific verb ('Get'), a specific resource ('mailbox plan'), and a key qualifier ('display-only'), which clearly distinguishes it from purchase or transfer quote tools. It also references listMailPlans as the source of packageId, further grounding the agent in the correct workflow.

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 provides concrete usage context: authentication is required, packageId must come from listMailPlans, and term accepts MONTHLY or ANNUAL with a default. It does not explicitly name sibling alternatives or state when not to use this tool, but the 'display-only' wording and the 'authoritative price at purchase' caveat make the intended pre-purchase use case clear.

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