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

Annotations already declare readOnlyHint=true, and the description builds on that by disclosing no-truncation pagination, inclusion of both upcoming and past events, and the exact return shape (dict with events array and count). It adds useful behavioral context such as ISO 8601 UTC timestamps and id prefix evt- that annotations do not provide.

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 front-loaded with the core action, then organizes behavioral details and return fields into clear summary and returns sections. Every sentence adds value, and the enumerated useful fields prevent ambiguity without bloating the description.

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-parameter read-only tool with no output schema, the description is fully self-sufficient. It covers scope, ordering, completeness, return structure, and relevant field formats, and it links to the sibling tool that consumes the output. Nothing essential is missing for correct invocation or interpretation.

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 zero parameters, so the schema is trivially complete and no parameter documentation is needed. The description focuses on return-value semantics instead, which is appropriate for a no-input read tool.

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 opens with a specific verb and resource: 'List all events on the user's Luma calendar, most recent first.' It further distinguishes itself by noting it fetches every page with no truncation, making it a complete-calendar listing rather than a filtered search. It also references get_luma_guests as the consumer of the returned event id, clarifying its role among siblings.

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 gives concrete usage contexts: answering 'which event is next', finding an event's id for get_luma_guests, and handling luma_event_created trigger fires. It does not explicitly state when not to use it or name exclusion alternatives, but the guidance is clear enough for an agent to select it appropriately.

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