set_calendar_color

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

With no annotations, the description carries the full behavioral burden; it does disclose one genuinely useful trait, that the change 'Can be undone' (probably via the sibling undo tool). It omits permissions/auth requirements, whether the change is idempotent, and whether it affects shared or subscribed calendars.

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 clauses with zero filler; the operation is front-loaded and the format and reversibility notes are appended only after the core statement. Nothing extraneous.

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 simple two-parameter mutation with no annotations and no output schema, the description covers the operation, the color format, and reversibility. It still leaves the calendar identifier and permission requirements unexplained, which matters given 0% schema description coverage.

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 0% - neither parameter has a description in the schema. The description compensates for 'color' by specifying the '#RRGGBB' format, but says nothing about 'calendar', leaving it unclear whether an ID, name, or path is expected.

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 ('Change') and resource ('an event calendar's colour'), and the '#RRGGBB' hint narrows the operation to a color assignment. It doesn't explicitly contrast with the sibling rename_calendar, but the resource and format make the intent unambiguous.

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?

There is no when-to-use guidance, no prerequisites, and no mention of alternatives such as rename_calendar or delete_calendar. The agent must infer that this is the tool for recoloring a calendar purely from the name.

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