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

Annotations only declare readOnlyHint=true, and the description adds substantial behavior: cross-event 404, ID documents never decrypted, admin reveal requires audit, phone numbers masked to the last 4 digits unless self-entered on this form, and an instruction not to proactively repeat contact data. These are genuine additions beyond the annotation, though the description does not describe response shape or field-level masking output.

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?

It is short and front-loads the auth/role requirement, but the semicolon-chained, telegraphic phrasing makes several clauses hard to parse on first read. Most sentences carry real policy weight, but the compressed style trades readability for brevity.

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 sensitive read tool with no output schema, it covers auth role, privacy constraints, cross-event scoping, sibling routing, and the follow-up path via the registrant's user.id. What is missing is any indication of what the returned payload contains besides contact fields.

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 baseline is 3; the description adds meaning by tying slug and submissionId together via the cross-event 404 rule, telling the agent the slug must match the submission's owning event. It does not add formatting or lookup guidance beyond the schema's own note about items[].id.

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 makes clear this reads one specified submission's answers and form contact details for a given event, and the title confirms 'viewing a registrant's details (incl. contact info)'. It distinguishes itself by naming list_signup_submissions for locating and review_signup_submission for handling, but the core action ('read one submission') is buried inside policy clauses rather than stated first.

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?

It gives an explicit precondition for use ('only when the person explicitly requests'), an explicit alternative for locating records (list_signup_submissions) and for taking action (review_signup_submission). It also names the failure condition (cross-event returns 404), so an agent can decide when this tool is and is not the right call.

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