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

Goes well beyond the annotations: it discloses that omitted fields are preserved, that empty calls are rejected, that enabling Guest Approval wipes the guest limit and waitlist, that the first guest limit enables the waitlist, that new questions replace the questionnaire only for future RSVPs, and that the updated event is returned. These are exactly the destructive side effects an agent needs before calling a destructiveHint=true tool.

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?

Front-loaded with the core action and the partial-update rule, then side effects, then return value and audience. Dense but every clause carries information; the enumerated field list is the one mildly redundant stretch given the schema already lists them.

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 11-parameter destructive mutation with no output schema, the description covers update semantics, rejection cases, side effects, authorization scope, and the return value. A minor gap remains on whether changes notify guests and on ordering constraints (deadline vs. start_at), though the latter is handled in the schema.

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 the baseline is 3; the description adds genuine cross-parameter semantics the schema only states in fragments – guest_approval/max_guests interaction and how questions replacement works over time. The plain field list (title, times, location, description, RSVP deadline) merely restates the schema, which keeps it from a 5.

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 ('Change the details or settings of an event you host') and immediately bounds the operation to a partial update of enumerated fields. It is clearly distinguishable from create_event, delete_event, and get_event without opening any sibling 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?

Provides a precondition ('Hosts only') and a usage rule ('Changes only the fields you give... a call with no field is refused'), plus a behavioral equivalence to the UI Edit page and settings panel. It stops short of naming sibling alternatives (e.g. use create_event for new events, cancel_event to cancel), so no explicit exclusion guidance.

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