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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false, so safety is covered. The description adds genuinely non-obvious behavioral context: the cover upload is not live yet, so the returned link currently resolves to the personal-message page instead. That caveat is exactly the kind of disclosure the agent cannot get from structured fields, though it does not describe the response shape.

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 with no filler: purpose first, then the important current-state caveat. The phrase 'Uploading a cover opens here soon' is slightly awkward phrasing but carries real information, so nothing should be cut.

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?

There is no output schema, and the description leaves the return format vague — 'the answer points to the page' suggests a URL or page reference but does not say whether it is a string, an object, or a rendered page handle. The availability caveat is a strong addition, but for a link-returning tool with no output schema, one more sentence on what comes back would round it out.

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 both the title `id` and the `language` enum are fully documented in the schema itself, including format examples and defaulting behavior. The description adds nothing about either parameter, so baseline 3 applies; no compensation is needed and none is given.

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 first sentence names a specific verb and resource: 'Get the page where a person can add their own cover picture to a printed copy.' That is a concrete artifact (an upload page for a custom print cover), and it implicitly distinguishes itself from siblings like get_listen_link and open_in_reader, which serve different media. It falls short of a 5 because it never names the sibling it complements (create_custom_print_order/quote_custom_print), leaving the routing inference to the agent.

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?

Usage is implied rather than stated: an agent can infer it should call this when a person wants to personalize a printed copy's cover. There is no explicit when-to-use, no precondition (e.g. after an order or quote exists), and no named alternative. The fallback sentence clarifies behavior but is not guidance about selection.

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