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

Goes well beyond annotations: discloses credit consumption with no reservation and a conservative creditEstimate, async job semantics, several-minute latency, the intermediate state where the book has no title/cover/pages, and the idempotent retry contract via requestId. This meaningfully complements readOnlyHint=false and idempotentHint=true.

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?

Front-loaded with the outcome and cost implications, then constraints, then retry guidance. Every sentence carries information, though the paragraph is dense and several clauses could be split for faster scanning.

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 an async, credit-consuming, no-output-schema generator, the description covers cost, latency, interim book state, page bounds, defaults, and retry semantics — enough to call it correctly. Minor gaps remain around the non-described creative parameters (artStyle, category, language).

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?

With only 38% schema description coverage, the description carries more of the burden and does add meaning for pages (5–24 vs. account cap), audienceAge (explicitly a content preference, not a request for a child's identity), readingLevel, and requestId reuse. However, topic, artStyle, category, and language are never addressed, leaving half the surface to inference from parameter names.

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 ('Generate a private illustrated book') and the surrounding behavior makes clear it is the only writer among a set of read-only siblings (get_account, get_book, get_job, list_books). An agent can distinguish it without opening the schema.

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?

Gives clear operational context: credits are consumed but no card is charged, pages must be 5–24 subject to the account cap, audienceAge/readingLevel should be supplied when requested, and requestId should be reused on retry. It stops short of naming when not to call it or explicitly comparing to the sibling read tools, so it is not a full 5.

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