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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so 'Read-only' is partly redundant. The description earns credit by disclosing the return shape with no output schema present: three named buckets (to_read / to_test / fading) with title + category, plus mean-state and counts, and it states that page text must be fetched separately.

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?

Three sentences, front-loaded with the trigger, then the return contract, then the safety/adjacency note. Every sentence carries distinct information and nothing is repeated.

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 and a single trivial parameter, the description supplies what the agent otherwise could not know: the bucket names, their contents, the aggregate fields, and where page bodies come from. Nothing needed to call or interpret this tool is missing.

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?

Only one optional parameter exists and schema coverage is 100%; the schema already says it scopes to a chapter and its subchapters and that omitting it covers the whole active volume. The description's 'active volume or a chapter' phrasing restates the same semantics without adding format or edge-case detail, so the baseline 3 applies.

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 description names a specific verb (list) and resource (pages to review), and enumerates the exact criteria that define membership: not read, not quizzed on, or forgetting (answered wrong or decayed). It also explicitly routes content retrieval elsewhere ('Page content itself comes from eigma_read_page'), separating this tool from a sibling.

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?

It opens with an explicit when-to-use trigger ('Use this when you want to target what the user should review'), and the scope note ('in the active volume or a chapter') tells the agent how to size the request. It names eigma_read_page as the follow-up for content, but there is no explicit when-not-to-use or a competing review-style sibling to disambiguate against.

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