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

The description discloses the locking side effect, the UI change ('page shows 已定'), the reopening behavior via null, and the admin-only scope. This goes well beyond the annotations, which only indicate a non-read, idempotent, non-destructive operation.

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?

Three short sentences cover scope, purpose, side effects, the reopen case, and required credentials. The most important information is front-loaded and every sentence earns its place.

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 small mutation tool with three fully documented parameters and no output schema, the description covers who may call it, what it does, what side effects occur, and how the null case behaves. No critical calling context is missing.

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 baseline is 3. The description mostly restates what the schema already says about start and adminKey; the main added nuance is the behavioral pairing of start=null with reopening, but that is also present in the schema's parameter description.

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 states a specific verb and object: 'settle on a start time', and clarifies the effect by 'locks availability picking and voting; the page shows 已定'. This clearly distinguishes it from voting tools like vote_time and generic mutation tools like update_event.

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?

It explicitly restricts usage to organisers ('Organiser only'), names the required credential ('adminKey from create_event'), and documents the reopen case with 'Pass start=null to reopen'. It does not name alternatives explicitly, but the context is clear enough.

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