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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds useful context by naming the returned fields and stating results are sorted, but says nothing about pagination limits or what happens at the end of the result set.

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?

A single front-loaded sentence covering resource, returned fields, ordering, and the underlying endpoint. Every clause carries information and nothing is padded.

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, enumerating the returned contact fields in the description is genuinely valuable. It is nearly complete for a read-only list tool, though it omits the pagination/next_page continuation behavior that the schema alludes to.

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 50%: page and page_size are documented in the schema, while sort and sort_direction are enum-only and self-explanatory. The description's phrase 'sorted by a column' hints at the sort parameter but adds no format or default details beyond the schema, so the baseline 3 applies.

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 (List) and resource (contacts in the account's address book), and enumerates the fields returned. No sibling tool touches the address book, so an agent can immediately tell this apart from the order/shipment tools in the namespace.

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 implies the use case (retrieve address book contacts) but offers no explicit when-to-use, prerequisites, or alternatives. Since there is no competing sibling for this resource, the missing routing guidance is less costly, but the guidance is still only implicit.

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