Calendar

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

The description explains the non-obvious side effect that 'selecting the month also changes the month this login's Librus session remembers,' which accounts for readOnlyHint=false even though this reads calendar data. That is exactly the kind of context annotations cannot convey. It stops at 4 because auth requirements and any rate/refresh implications are not mentioned.

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 tight sentences, each doing distinct work: scope, sibling routing, and side effect. The core purpose is front-loaded with zero filler.

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?

An output schema exists, so return values need no explanation. The description covers scope, follow-up tool, and the session side effect, which is everything an agent needs to call it correctly in this context.

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%, so year, month, and account_alias are already documented in the schema (account_alias even points to list_accounts). The description's 'one month' loosely ties to month/year but adds no syntax or format detail beyond the schema. Baseline 3 is appropriate.

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?

Specific verb (List) plus resource (one month of school calendar events) with concrete examples (tests, trips, days off) that make the scope unambiguous. It also implicitly distinguishes itself from get_agenda_detail by framing this as the monthly listing that yields event references.

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 clearly states the follow-up path: 'Pass an event's reference, when present, to get_agenda_detail.' That routes the agent to the correct sibling. It stops short of explicit when-not-to-use guidance, so it falls just shy of a 5.

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