borrow

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

Annotations already declare this is a non-read-only, non-destructive open-world action, so safety framing is partly covered. The description adds two valuable traits beyond that: the availability precondition and a mandatory user-confirmation step. It still omits what happens on a ready-hold borrow (whether the hold is consumed/converted into a loan) and failure behavior, which matter for a write operation.

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 short sentences, zero waste, with the action and its precondition front-loaded before the safety instruction. Nothing is padded or repeated from the schema.

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 an output schema and annotations present, the description only needs to cover trigger, preconditions and side effects. It covers trigger and precondition well; the one remaining gap is the hold-consumption side effect, which an agent borrowing a ready hold would benefit from knowing.

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%, with days, library and title_id all documented in-schema (including the 1-21 range and the "defaults to the card's preference" note). The description adds no parameter-level meaning, 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?

"Borrow an available title, or a hold that is ready" gives a specific verb plus the two resource states it operates on, which meaningfully separates it from place_hold, renew_loan and return_loan. It stops short of naming those siblings, so the differentiation is implied rather than explicit.

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?

The description sets a clear precondition (the title must be available, or a hold must already be ready) and adds an operational rule: confirm with the user first. It does not say what to do in the negative case, e.g. route to place_hold when nothing is available, so it is good context without explicit alternatives.

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