add-calendar-event-attachment

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

Annotations already declare destructiveHint=true and openWorldHint=true, so safety is covered. The description adds real behavioral context beyond that: the <3 MB size constraint and the non-obvious organizer/attendee propagation behavior when a meeting attachment is later sent. It does not discuss auth requirements, but the added behavioral detail is substantive.

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?

Purpose and size limit are front-loaded, the payload template is compact, and the routing tip is clearly delimited. The organizer-propagation sentence is slightly tangential but still informative, so overall it earns its length.

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 mutating tool with annotations, no output schema, and nested parameters, the description covers purpose, the limiting constraint, the alternative, and the payload format. The confirm gate is documented in the schema. Remaining gaps (auth, return shape) are minor since annotations and schema carry them.

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 description coverage is 80%, but the crucial body fields @odata.type and contentBytes are absent from the schema, and the description supplies the exact payload shape. That is genuine added meaning over the structured data. The confirm/includeHeaders/excludeResponse params remain explained only in the schema, which is acceptable.

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+resource ('add an attachment to an existing event') and immediately scopes it with the 3 MB limit, cleanly separating it from the sibling upload-session tool. An agent can tell what this does and when it does not apply without opening any schema.

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?

Explicit when-to-use boundary is given twice (under 3 MB) and it names the alternative tool (create-calendar-event-attachment-upload-session) for the ≥3 MB case. The condition that selects the sibling is fully specified rather than left to inference.

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