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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. Beyond that, the description discloses the returned field set (id, custom id, name, email, company, fields) and the filterable dimensions, and pins the underlying call to GET /contacts, which is useful context an agent cannot get from the annotations alone.

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 short clauses with the resource front-loaded, followed by return fields and filterable fields, and ending with the endpoint. Nothing is padded, though the trailing GET /contacts is the least essential element.

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 usefully characterizes the shape of each returned contact. It covers filtering and return content; pagination is left entirely to the schema, which is an acceptable but minor gap for a paged list tool.

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 every parameter is already documented, including pagination via max_results/first_result and the RFC 3339 pattern for updated_since. The description's filter list roughly echoes what the schema says and adds no format or semantics detail beyond it.

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 ('List the contacts of the address book') and enumerates the returned attributes, so it is clearly a collection read rather than the single-record evenium_get_contact. It does not explicitly name a sibling to distinguish against, keeping it just short of a 5.

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 names which fields can be filtered on (name, email, company, last update), which implies the use case, but gives no explicit when/when-not guidance or routing to alternatives such as evenium_get_contact for a single lookup.

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