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

Annotations already cover the safety profile (readOnly, non-destructive, openWorld), and the description adds genuinely non-obvious behavior: page cap of 20, and that IP address and coordinates are stripped from results. It stops short of covering default status filtering or sort behavior, which live only in the schema.

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 operation and target, followed by data shape, paging, privacy note, and endpoint in two tight sentences. The 'paged, 20 at most' clause slightly duplicates the schema but earns its place as a top-level constraint.

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 no output schema, the description usefully characterizes returned fields and privacy redaction. It leaves the status-omission default and sort defaults to the schema, which is acceptable given the high schema coverage, so an agent has enough to call correctly.

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 83%, so the schema already documents page, page_size, status, sort_by, sort_order and calendar_ids thoroughly. The description only echoes the page-size cap already stated in the schema, adding no new syntax or filtering semantics.

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?

Names a specific verb and resource ('List people subscribed to the account's calendars'), states the returned data shape, and gives the underlying route (GET /subscribers). This distinguishes it clearly from the singular get_calendar_subscriber sibling.

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 notes paging limits but never says when to use this tool instead of get_calendar_subscriber or list_calendars, nor does it mention the status/omitted-filter caveat that drives pagination strategy. No explicit when/when-not guidance is present.

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