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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds valuable behavioral context beyond annotations: it names stored .ics files with no calendar row and describes the fallback behavior of printing export steps when there are none. This is genuinely useful edge-case disclosure that the annotations do not provide.

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?

The description is two sentences, front-loaded with the core purpose and fields. The first sentence immediately states the action and result set; the second sentence adds two edge-case behaviors. There is no filler, redundancy, or irrelevant detail. Every clause earns its place.

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?

For a simple listing tool with no parameters and no output schema, the description covers what is returned (fields and edge cases) and even the no-result fallback. It does not specify the exact output formatting, but that is minor given the tool's low complexity. An agent can predict behavior and interpret results without ambiguity.

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?

The tool has zero parameters, so the schema provides no parameter documentation. Per the rubric, a 0-parameter tool gets a baseline of 4. The description does not need to add parameter meaning, and it does not attempt to invent any. The description's focus on output is appropriate given the lack of parameters.

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 starts with 'List imported calendars' — a clear verb-resource pair — and enumerates the exact fields returned (name, event-definition count, size, source, import time, free-tier use of 2 slots). It also distinguishes itself from siblings by noting it handles .ics files without calendar rows and prints export steps when empty, which is specific and non-overlapping with import/export tools.

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 clearly states what the tool does, but it does not explicitly say when to use it versus alternatives like ics_import or ics_forget. The context makes it self-evident (you call it to view your calendars), yet there is no explicit 'use this when...' or 'instead of...' guidance. It relies on the tool's purpose being obvious.

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