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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true. The description reinforces this with the non-obvious clarification "Read-only quote: it places nothing" and discloses that the underlying call is POST /shipping/{shipping_id}, which usefully prevents an agent from assuming POST means mutation. It does not mention rate limits, currency, or whether the quote expires.

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 sentences with zero filler: the purpose and scope lead, followed by the read-only caveat and the prerequisite endpoint reference. Every sentence contributes information an agent needs.

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 four-parameter quote tool whose annotations and schema are fully populated and which has no output schema, the description covers purpose, safety, and the prerequisite lookup. Minor gaps remain: what the returned cost represents (currency, whether it excludes tax/duties) and whether a state is required for non-US destinations.

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%, so all four parameters are already documented, including the note that shipping_id comes from customcat_list_shipping_methods. The description adds only a general restatement of the inputs (destination, SKUs, quantities) with no format details, defaults, or constraints beyond the schema, so the baseline of 3 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 and resource ("Calculate the shipping cost") plus the exact scope of inputs: one shipping method, a destination, and a list of catalog SKUs with quantities. It is clearly distinguishable from sibling tools, and it explicitly names customcat_list_shipping_methods as the source of shipping_id, separating it from the listing endpoint.

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 clear usage context: this is a read-only quote for pricing a shipment, and shipping_id must come from customcat_list_shipping_methods, which routes the agent to the prerequisite call. It does not state explicit exclusions (e.g., that it does not create an order or that customcat_create_order is the next step), 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.