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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description's job is to add context. It does: the return shape {chars_total, chars_returned, truncated, markdown, markdown_url} and the truncation behavior. It omits auth/rate-limit notes, but discloses meaningful behavioral detail beyond annotations.

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 core purpose, then clearly delineated 'When to use', 'Do not use', and 'Returns' sections. Every sentence is functional with no filler.

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?

No output schema exists, and the description provides the return shape and truncation semantics. Combined with explicit routing guidance and alternatives, an agent has everything needed to call this correctly versus siblings.

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% - max_chars is documented in the schema while lang and slug are not. The description adds no meaning for lang/slug and only indirectly references truncation via the return fields, so it does not compensate 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+resource ('whole-book Markdown mirror') with scope (entire book, including metadata header and summary). It distinguishes itself from siblings by naming chapter/toc alternatives and the book-level summary it uniquely provides.

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?

Explicit 'When to use' clause (complete text needed, after checking chapter_count/word_count via cyberlibrary_book_meta) and explicit 'Do not use' with the alternative (cyberlibrary_get_toc + cyberlibrary_get_chapter, 'far cheaper'). Both the positive and negative conditions are spelled out.

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