Register for a contest

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

Annotations already carry mutation and idempotency, so the description only needs to add context; it does, by emphasizing that this is a real, committed registration on the authenticated account. It also clarifies that virtual mode schedules a virtual run rather than just storing a preference. No statement contradicts annotations.

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, with the core action first and mode guidance second. The final warning ('This is a real registration') is useful disambiguation rather than filler.

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-action registration tool, the schema plus output schema cover types and return shape, and annotations cover safety; the description supplies the state-changing context and mode conditions. It could mention preconditions such as eligibility or invite requirements, but the open-world and idempotency hints reduce the need.

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 covers all three parameters, so the baseline is 3; the description adds value by explaining that mode='normal' targets the live window and mode='virtual' is paired with virtual_start_time to schedule a virtual run. It reinforces the ISO-8601 requirement already in the schema but doesn't add independent parameter semantics for contest_id.

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 action — 'Register the authenticated account for a contest' — with a clear resource and actor scope. The mode distinction ('normal' vs 'virtual') further separates it from read-only contest siblings, so an agent can identify it without opening the 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?

The description gives explicit in-tool usage for mode selection: normal for the live window, virtual only with an ISO-8601 virtual_start_time. However, it does not mention prerequisites such as eligibility or invite checks, nor does it explicitly contrast this tool with sibling tools like check_invite_eligibility or get_contest_registrations.

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