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

readOnlyHint=true already tells the agent this is a safe read. The description contributes only the endpoint path and the optional-window note, with no mention of result ordering, pagination, caps, or default time range for a list endpoint where those traits matter.

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?

Three terse fragments, front-loaded with the core purpose and free of filler. Slightly telegraphic – the fragments read as note stubs rather than sentences – but nothing is wasted.

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 two-optional-param read tool with annotations and full schema coverage, the minimum is met, but absence of any default-window or return-shape note leaves the agent guessing about what a windowless call returns. No output schema exists, so a brief return summary would have helped.

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 100% and both parameters are fully documented in the schema, including that they map to ISO date/datetime query params. The description's 'Optional start/end window' merely restates the schema, 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 resource ('List calendar events') and disambiguates from siblings list_tasks/list_habits by naming events explicitly. The REST endpoint reference reinforces the resource but adds nothing that helps selection.

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?

Only 'Optional start/end window' hints at usage; there is no when-to-use guidance, no mention of what happens with an omitted window (all events? default range?), and no routing to or from sibling tools like get_task or list_habits.

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