upc_library_times

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

Annotations already declare readOnlyHint, openWorldHint, and destructiveHint=false, so the safety profile is covered. The description adds genuine behavioral context that annotations cannot convey: the same tool returns different data depending on whether start_id is populated. It says nothing about result size, ordering, or what happens when no times exist for a date.

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?

A single twelve-word sentence with no filler, and the primary mode (start times) is front-loaded ahead of the conditional secondary mode. Nothing could be removed without losing the mode distinction.

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?

This is a simple read tool with no output schema and full annotation coverage, so the bar is low, but the description never establishes the domain link between seat_id, date, and the returned times. An agent knows what the tool returns but not how the values are shaped or how they feed into booking.

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 75% and the schema already explains start_id in Chinese, so the description largely restates the mode switch. It does add a small amount of meaning by framing start_id as 'a selected start' the caller has already seen, reinforcing that the ID must come from a prior call rather than be fabricated. seat_id and session_ref receive no mention in either the description or useful schema detail.

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 gives a specific verb (Read) and a specific resource (school-provided start times / end times for a selected start), and it makes the two-mode nature of the tool explicit. It stops short of differentiating itself from nearby siblings such as upc_library_seats, upc_library_reservations, or upc_library_book, and the phrase 'school-provided' does little to clarify what a 'start time' actually is.

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 two clauses imply a chaining workflow — call without a start to get candidate starts, call again with a chosen start to get ends — but this is left implicit rather than stated as a rule. Nothing tells the agent when to prefer this over upc_library_seats or upc_library_book, nor whether it is a prerequisite for upc_library_book.

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