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

Goes beyond the annotations by explaining downstream consequences (saved lines surface alongside other quotes and appear in quote review) and by spelling out the practical meaning of idempotentHint=false: 'Each call saves the line again.' That is exactly the kind of duplicate-accumulation warning an agent needs for a non-idempotent write.

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-loads what gets saved and where, then usage rules, then a copy-ready example call. Every sentence carries distinct information; nothing is repeated from the schema apart from a harmless field mention.

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?

Annotations cover the safety profile, an output schema exists, and the description supplies the remaining agent-relevant context: where saved lines appear, the review workflow they feed, and the duplicate-save hazard. Nothing needed to call it correctly 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?

Schema description coverage is 100%, so both parameters and the anchor format are already documented in the schema, including the same example anchor. The description adds only a light restatement ('with an optional note'), 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?

States a specific verb and resource ('Saves one line of a poem') plus the destination ('the reader's ReadingRate quotes') and the anchoring constraint. It is clearly separable from sibling writes like save_quote and annotate_poem_line without opening any 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 an explicit trigger ('Use when the reader asks to save, keep or remember a line of a poem') and names the alternative for the adjacent-but-different intent ('To write a note about a line without saving it as a quote, use annotate_poem_line'). The 'save a line once' rule closes the remaining ambiguity.

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