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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so an agent knows this is a safe, repeatable, non-mutating operation. The description adds a genuinely useful billing detail (cost: 1 credit) but says nothing about what is returned or whether a timezone-less input falls back to a default.

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?

One short sentence plus a parenthetical cost note, front-loaded with the action and resource. Nothing is wasteful, though the brevity comes partly from omitting information rather than from tight editing.

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 six parameters and no output schema, the description should explain the returned artifact (ICS text, download URL, or file), yet it is silent on return values. For a builder/generator tool this is a meaningful gap that the annotations cannot fill.

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 all six parameters carry some documentation there, which sets the baseline at 3. The description adds no meaning beyond the schema and does not clarify format expectations such as the ISO datetime layout, IANA timezone examples, or the relationship between start and end.

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?

"Build an .ics calendar event" gives a specific verb and resource (an iCalendar payload), which is clearly distinct from the sibling utility tools such as hash_text, json_validate, and qr_code. It stops short of saying whether the result is a returned ICS string or a stored file, which leaves a small ambiguity about the artifact produced.

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 offers no when-to-use guidance, no prerequisites, and no alternatives; the only extra context is a cost note. An agent must infer the use case entirely from the tool name.

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