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

The description discloses that the tool returns a URL for subscription, which is the main behavioral trait. However, it does not mention any potential side effects, permissions, or limitations (e.g., whether the URL is static or changes). Since no annotations are provided, the description carries the full burden, and it is adequate but minimal.

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 long, front-loads the core purpose, and contains no unnecessary words. Every sentence adds value.

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 tool with no parameters and a simple return value (a URL), the description fully explains what the tool does and how to use the result. No output schema exists, so the description effectively covers the return value.

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 no parameters, so the description does not need to add parameter meaning. Baseline for 0 parameters is 4, and the description 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?

The description clearly states the tool retrieves a public iCal subscription URL for the calendar, distinguishing it from sibling tools like calendar_list_events which list events, and calendar_create_event which creates events.

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 explains that the returned URL should be shared with calendar apps for subscription, giving clear usage context. It does not explicitly mention when not to use or alternative tools, but the context is sufficient given sibling differentiation.

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