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

Annotations already cover the read-only, non-destructive profile, and the description adds real context beyond them: the exact REST endpoints, the fact that REGISTRATION means session registrations, and that event-only fields are flagged. It stops short of describing error behavior for invalid ids or missing guests.

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 dense sentences, front-loaded with the resource and payload, then the optional includes and endpoints. The trailing GET paths are somewhat redundant with the schema parameters but still orienting; nothing is 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?

With no output schema, the description carries the return-value burden and does so by naming the fields returned. Combined with the include options and lookup keys, an agent has enough to call it correctly; only the dual-key conflict rule is missing.

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 a bump by expanding the opaque 'include' enum values into meaning ('REGISTRATION (registrations to sessions), PRESENCE and SIGNATURE data'), which the schema only labels as 'Extra data to return.'

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 ('One guest of an event') and enumerates the returned fields (name, email, status, category, fields). The phrase 'event-only fields flagged' implicitly distinguishes it from evenium_get_contact, and 'One guest' contrasts with evenium_list_guests.

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?

The description indicates the two lookup keys ('by contact id or by guest code') but never says when to prefer this tool over evenium_get_contact or evenium_list_guests, nor what to do if both keys are supplied. Usage is implied by the retrieval phrasing rather than stated.

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