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

The readOnlyHint=true annotation already establishes this is a safe, non-mutating read, so the description carries a lighter burden. It adds the account-scoped endpoint mapping and the optional event narrowing, but says nothing about pagination behavior, default page size, or result ordering despite exposing current_page and sort_direction parameters.

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?

Two short sentences with the core scope front-loaded and the REST endpoint appended for implementers; there is no filler. Slightly terse given the tool exposes filtering and paging, but nothing is wasted.

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 read-only, account-scoped list with full schema coverage and no output schema, the description covers what the tool returns conceptually (registrations, optionally per event). Return shape and pagination are the only omissions, and the naming plus schema carry most of that.

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 description coverage is 100%, so the schema already documents all four parameters, including the 0-based paging semantics and the enum-constrained sort direction. The description only restates the optional event filter already covered by event_id, adding no syntax or behavioral nuance beyond the schema.

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?

The description states a specific verb ("List") and resource ("event registrations") scoped to "one account", and notes the underlying endpoint GET /accounts/{id}/eventRegistrations. It implicitly distinguishes itself from the broader sibling neon_list_event_registrations by binding the listing to an account, but never names that sibling or contrasts explicitly.

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?

"optionally for a single event" gives one useful scoping hint, so the reader understands the event filter is optional. However, there is no explicit when-to-use vs. when-not, no statement of prerequisites (e.g., valid account id), and no routing to sibling tools such as neon_get_account or neon_list_event_registrations.

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