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

Annotations already declare the safety profile (non-read-only, non-destructive, non-idempotent, closed-world), so the bar is lower. The description still adds real behavior: the 24-hour download link with expiry, the returned event count, and the explicit no-side-effect boundary. It does not explain why repeated calls yield different links (the non-idempotent trait), which is the one remaining gap.

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-loaded with the trigger condition, then input shape, then returns, then the scope boundary — a logical order with no filler sentences. It is dense and long-ish, but each clause carries information an agent needs.

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?

Covers the trigger, the 1-50 event shape, the required title/start pair, optional fields, and even summarizes the return value. With an output schema present the return summary is a bonus rather than a requirement, so nothing an agent needs to call this 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 the schema already documents start/end formats, timezone, recurrence fields and limits. The description largely restates these (title/start/end-or-duration, timezone IANA, recurrence freq/byday/until/count) rather than adding new 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?

States a specific verb and artifact ('make a calendar (.ics) file') and immediately scopes it against the sibling make_csv_file by naming the output format. An agent can distinguish it from the other file-making tool without opening either 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?

Opens with an explicit trigger ('Use this when the user wants a calendar file') plus three concrete user utterances, and closes with a hard exclusion: 'It makes a file only; it does not add anything to a calendar.' When-to-use and when-not are both spelled out.

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