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

Annotations already declare readOnlyHint=true, so the safety profile is covered; the description adds real value beyond that by flagging that the response contains personal data and by stating the required API key permission scope. It doesn't describe error behavior for a bad or missing id, which keeps it from 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?

Front-loaded with the core action and outcome, then tightened with short follow-up sentences for the personal-data warning, the permission requirement, and the endpoint. The opening sentence is long and carries a heavy nested parenthetical, but nearly every clause adds information an agent needs.

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?

There's no output schema, and the description compensates by enumerating the returned fields, including the payment sub-fields. Combined with the PII notice and permission requirement, an agent has everything needed to call this single-record read correctly.

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 earns above baseline by explaining what include=payment actually unlocks (amount, fees, taxes, refunds, transactions, card brand and last 4 digits), which the schema's terse enum list does not convey. It says nothing extra about expand, but that's a minor omission.

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 ('Get one attendee registration in full') and enumerates exactly what comes back: contact data, registration answers, remark, status, and payment details. The word 'one' plus a required attendee_id cleanly separates it from the sibling corsizio_list_attendees, so an agent can pick correctly 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 a concrete conditional: use include=payment to get amounts, fees, taxes, refunds and transactions. It also names the prerequisite ('The API key needs the attendees permission'). What's missing is an explicit statement of when to prefer this over list_attendees or get_event_with_attendees, so it stops short of a full routing guide.

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