calendar_update

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

With no annotations, the description carries the full behavioral burden, and it excels: it discloses partial-update semantics, immutability of `kind`, conditional parameter grouping, the free-text nature of `channel`, the hard-fail risk if `publish_tool` is not connected, and the difference between cancelling and deleting. This is exactly the kind of context an agent needs to avoid destructive or invalid updates.

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 dense but every sentence earns its place, and the most important fact—this modifies an existing event—is front-loaded. The later clauses efficiently pack conditional rules, cancellation semantics, and critical constraints on `publish_tool` without repeating the schema.

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 an 11-parameter mutation tool with no output schema and no annotations, the description provides strong coverage of the update contract, including partial updates, cancellation/re-arm, and conditional rules. The only minor gap is that it does not describe what the tool returns on success or failure, but that does not materially impede an agent's ability to select and invoke it 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 100%, so the baseline is 3, but the description adds cross-parameter semantics beyond the schema: it states that omitted fields are unchanged, that schedule changes require exactly one of `at`/`rrule`, that post events require `content`+`channel`+`publish_tool` together, and that `kind` cannot be changed. These relationships are not fully captured by individual parameter descriptions.

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: 'Change fields on an existing calendar event,' which clearly distinguishes this from the sibling create/list/remove tools. It also names the two additional allowed actions—re-arm and cancel—so the agent immediately understands the tool's scope.

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 makes clear this is for existing events, not new ones, and refers to calendar_add for shared rules, which orients the agent toward the correct sibling. It lacks an explicit statement like 'use calendar_remove to delete an event,' so alternatives are implied rather than fully enumerated.

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