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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, so the safety profile is covered; the description adds genuinely new behavior — that a duplicate may be silently created and that it hits POST /contacts. It stops short of describing the response (e.g. returned contact id) or any auth/scope requirements, which keeps it off 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 with the write nature and resource front-loaded, followed by the routing caveat and the duplicate warning. Every clause carries actionable information and nothing repeats the schema.

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 7-param mutation with no output schema, the description covers purpose, routing, and the main risk (duplicates). The remaining gap is what comes back after creation — an agent cannot tell whether a contact id is returned for chaining into evenium_create_guest.

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 only 29% across 7 params, so the description must compensate; it does name most of them (name, email, company, custom id, fields) but adds no semantics beyond the property names. The 'gender' enum and the ext:<id> mechanics of custom_id are left entirely to 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?

Opens with an explicit verb+resource ('add a contact to the address book') and enumerates the payload it accepts (name, email, company, custom id, fields). It also names the sibling it is not (evenium_create_guest), so the agent can distinguish it from guest-creation tools without opening a 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?

Explicitly states a when-not ('Does not invite them to an event') with the alternative tool named, plus a precondition workflow ('search with evenium_list_contacts first') to avoid duplicates. Both the exclusion and the recommended prerequisite are spelled out rather than implied.

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