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

Annotations already declare the write/idempotent/openWorld profile, and the description adds genuinely new behavior: creating a guest may also create a new contact, and the invitation emails sent may follow Evenium's own rules. Useful side-effect disclosure for a mutation. It stops short of saying what happens on a duplicate invite or what the response contains.

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 tight sentences, front-loaded with the 'WRITE:' marker so the mutation semantics land first, followed by the mode split and the status caveat. The trailing 'POST /events/{eventId}/guests' restates the operation rather than adding agent-relevant information, which is the only wasted line.

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 8-parameter mutation with no output schema, the description covers the mode decision, the contact-creation side effect, and the email-behavior caveat, which is most of what an agent needs before calling. Gaps remain around duplicate/already-invited handling and the result payload, but the core call decision is well supported.

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 only 38%, so the description has to carry more weight: it does explain the contact_id vs. name-field fork and elaborates on status as the registration status influenced by event email rules. But gender, company, and email constraints are left entirely to the bare schema, and the description never states which from-scratch fields are actually required.

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 and resource ('invite a person to an event') and immediately decomposes it into its two distinct modes: inviting an existing contact via contact_id, or creating a guest from scratch via name/email fields. An agent can distinguish this from evenium_create_contact and evenium_update_guest_status without opening any 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 two invocation paths are stated with their selecting parameters ('Either invite an existing contact (contact_id) or create a guest from scratch (...)'), which is explicit when-to-use guidance. It lacks a negative case, e.g. when to prefer evenium_create_contact first and then invite, so it falls short of the full when/when-not/alternatives bar.

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