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

Annotations declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, but tell the agent nothing about prerequisites or side effects. The description adds valuable context that annotations lack: the connected-account requirement and the conditional behavior (approval events degrade into a host request). It does not explain idempotency_key semantics or what the response looks like, so it stops short of a 5.

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 core action, then the approval-event nuance, then the paid-tier routing and the account prerequisite. Every sentence earns its place with no 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 3-parameter mutation with no output schema, the description covers the main routing decision and the account prerequisite. It is missing semantics for two of three parameters and any note on what happens on success (e.g., pending state), which keeps it from being fully complete.

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 0%, so the description must carry parameter meaning, but it only implicitly touches event_id. It says nothing about idempotency_key or ticket_class_id - the latter is especially notable since its presence contradicts the 'free event' framing. The schema at least provides type and length constraints, so this is a marginal 3 rather than lower.

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 (RSVP) and object (yourself to an event) and immediately distinguishes approval-gated events (become a host request) from free events. It also names the sibling 'start_ticket_checkout' for the paid case, so an agent can route without opening schemas.

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?

Explicitly partitions usage: free events go here, approval events here too (with different semantics), paid tiers go to start_ticket_checkout. It also names a hard prerequisite - 'Requires a connected account' - which is exactly the kind of when-to-use gating an agent needs.

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