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

Annotations already establish readOnly/idempotent/non-destructive, and the description adds substantive behavior on top: response composition (subsections, code blocks with run versions and pass status, citations), pagination mechanics, and ID-redirect behavior where the answer reports the section's current name. It does not state rate limits or size limits, which keeps it below a 5.

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?

Four sentences, each carrying distinct information, with the payload description front-loaded and pagination plus ID behavior following. The opening sentence is dense with parentheticals but nothing is redundant.

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?

An output schema exists so return values need not be detailed, but with four parameters at 0% schema coverage the description should clarify `book` and `edition` (e.g., accepted identifier format, default edition behavior) to be fully sufficient. Pagination and ID-redirect behavior are adequately covered.

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 0%, so the description carries the burden. It does valuable work on two parameters - `cursor` (use the `next_cursor` from the previous response) and `section_id` (chapter IDs accepted, old IDs tolerated) - but leaves `book` and especially `edition` completely unexplained, so it only partially compensates for the coverage gap.

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 ('Read one section of a book as Markdown') and enumerates what the read includes: subsections, code examples with versions and pass status, and the citation block. It does not name a sibling to contrast with, so the agent must infer the boundary with get_contents or search_books, but the scope is otherwise unambiguous.

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 real operational guidance: a chapter ID yields the chapter opening, a long section is paginated via the returned `next_cursor`, and stale IDs still resolve. It never says when to choose this over get_contents or check_code, so the when-to-use versus alternatives is only implied by the description of what is returned.

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