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

Annotations already declare destructiveHint, idempotentHint and openWorldHint, so the safety profile is covered. The description goes beyond them by stating the login requirement and the terminal-state rule (cannot cancel an already cancelled/ended activity), both of which are actionable behavioral facts not in the structured data.

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 sentences with the auth prerequisite front-loaded and no filler. Every clause (login requirement, action, state constraint) earns its place, though there is little room to demonstrate structure.

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 single-parameter cancel tool with annotations covering safety and no output schema to explain, the description supplies the missing pieces: auth need, scope, and the state precondition. An agent has enough to call it correctly, though naming the sibling it is not would fully close the gap.

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% and there is a single parameter, so the schema already documents activityId fully. The description adds no syntax, format, or meaning beyond that, making the baseline 3 correct.

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 plus scope: cancel (take offline) an activity I initiated. The modifier '我发起的' implicitly disambiguates from the sibling cancel_my_activity_signup, which cancels a signup rather than a hosted activity, giving real sibling separation.

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?

Provides a precondition (already-cancelled or already-ended activities cannot be re-cancelled), which is genuine usage context, but never names an alternative tool or explains when to prefer this over e.g. cancel_my_activity_signup or update_activity. Guidance is implied rather than explicit.

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