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

Annotations already declare this is a non-read-only, non-destructive, non-idempotent mutation. The description goes beyond them by disclosing an authorization requirement (must be a host) and a quota side effect (counts against the weekly invite limit), which are not encoded anywhere in the structured fields.

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?

A single dense sentence that front-loads the action and resource, then lists fields and constraints in priority order. It is slightly run-on, but every clause carries information and nothing is padded.

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 10-parameter mutation tool with no output schema, the description supplies prerequisites, quota impact, and field inventory, which is close to what an agent needs. It stops short of covering duplicate-handling behavior and the shape of the result, leaving minor gaps.

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?

With 0% schema description coverage, the description must carry the parameter burden, and it names essentially all ten fields including optionality markers (last_name optional, email/phone/category optional) and gives a category example (vip/press) that substitutes for the missing enum. It does not clarify that plus_ones_allowed is a numeric cap (max 100) or that ticket tier maps to ticket_class_id, so semantics are partial.

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 (add) plus resource (guest to a live event's guest list) and enumerates the fields involved, which cleanly separates it from siblings like edit_guest, remove_guest, list_guests, and import_guest_list. An agent can identify the operation 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?

Gives concrete preconditions: requires event_id and host privileges, and warns it consumes the weekly invite limit. It does not, however, name alternatives such as import_guest_list for bulk adds or approve_guest_request for pending requests, so routing between siblings still requires inference.

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