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

Annotations already cover safety and idempotency (readOnly, idempotent, non-destructive, closed world), so the bar is lower, and the description still adds real context: results are filtered to open titles and chapter text is deliberately excluded. It does not say whether a non-open title yields an empty list or an error, which is the one behavior an agent would still need.

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, no filler. The returned data is stated first, then the two hard constraints (open titles only, no chapter text), both front-loaded.

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?

With no output schema, the description correctly tells the agent what comes back (chapters and their access) and what does not (chapter text). For a simple two-param read tool this is nearly sufficient; the only gap is how the access value is shaped and what happens for restricted titles.

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 coverage is 100% and both parameters (id, language) carry detailed descriptions including format examples and default-language logic, so the schema does the work. The tool description adds nothing about parameters, which is acceptable at this coverage level but earns only the baseline.

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 ("List the chapters") plus the extra returned field (access) and the audience (signed-in member). It also bounds scope with "Only open titles are shown, and no chapter text is returned." It never names a sibling (e.g. get_book, get_chapter_summary, get_passage) to contrast with, so differentiation is inferred rather than stated.

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?

"for the signed-in member" implies an auth prerequisite and the open-titles constraint implies when results will be thin, but there is no explicit guidance on when to pick this over get_book or get_chapter_summary, nor what to do when a title is not open. Usage is implied by context, not spelled out.

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