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

The readOnlyHint=true annotation already establishes this as a safe read, so the description carries a lower burden. It contributes the fact that ids are included in the result, but says nothing about pagination, ordering, or what fields besides id come back.

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?

Two short, front-loaded sentences with no padding; the purpose and return content come first. The trailing 'Elvanto: calendar/getAll' is mildly extraneous traceability text but costs little.

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 zero-argument list tool with no output schema, the description gives only a partial picture of the response (ids, implicitly names). It is adequate to invoke but leaves the returned shape largely unspecified.

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 takes zero parameters, which is the baseline-4 case; there is no parameter surface for the description to explain. The description's mention of returned ids is the only semantic content relevant to invocation.

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 ('List') and resource ('the church's calendars') and adds the useful detail that ids are returned. It is clearly separable from siblings like elvanto_list_calendar_events or elvanto_list_groups, though it does not explicitly name those alternatives.

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?

Usage is only implied: the agent can infer this is the lookup used when calendar ids are needed, since it returns ids. There is no statement of when to prefer this over elvanto_list_calendar_events nor any prerequisites, and the 'Elvanto: calendar/getAll' line is API mapping rather than guidance.

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