List contacts

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false; the description adds behavioral detail beyond that: ordering by most recently changed and the token-based pagination contract. It does not cover rate limits or auth, but those are not essential given the annotations and the account parameter.

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 sentences, front-loaded with the core behavior, then token mechanics, then the sibling alternative. No filler or redundant clauses.

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 read-only paged list tool, the description plus high-coverage schema and annotations is enough to invoke correctly. It covers ordering, pagination, and the search alternative; the absent output schema is not a blocker because the return shape is not needed to make the call.

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 account, page_size, and page_token are already documented. The description mainly reinforces the page_token round-trip, which is already in the schema, so it adds little parameter meaning beyond the baseline.

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 identifies a specific action (paging through the address book) and resource (account address book), and adds the sort order. It also names contacts_search as the sibling for targeted lookup, so an agent can differentiate the tools without opening schemas.

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 explicitly states when to prefer contacts_search ('looking for someone in particular'), implying contacts_list is for browsing or enumerating contacts. It also frames the pagination workflow, making clear this is the paging tool.

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