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

Annotations cover the read-only safety profile, so the bar is lower, and the description adds real behavioral context: it explains what the data actually is (auto-collected, never explicitly saved), documents the pagination loop concretely (pass next_page_token back as page_token, stop when null), and states the account prerequisite. The only reason it is not a 5 is that no pagination default (limit) or ordering is mentioned, though that is minor here.

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?

It is front-loaded with the scope and the sibling contrast, then gives pagination and account guidance in sequence, with no wasted clauses. It is slightly denser than necessary but every sentence earns its place.

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, paginated list tool with full schema coverage and annotations covering safety, the description supplies everything an agent needs: scope, what the data means, the pagination protocol, and the multi-account condition. No output schema exists, and none is needed for a simple list endpoint.

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 all three parameters are already documented, giving a baseline of 3. The description reinforces the pagination mechanism and the multi-account condition for `account`, but adds no format, syntax, or default details beyond 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?

The description states a specific verb and resource ('Browse ALL of Google's auto-collected "other contacts" for one account') and explicitly defines the resource in contrast to the sibling list_contacts ('the counterpart to list_contacts for the "other" source'). An agent can distinguish this from list_contacts and search_contacts 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?

It states 'No query needed,' which differentiates this from search_contacts, and names the sibling it is the counterpart to. It does not explicitly enumerate when NOT to use it (e.g. for saved contacts), leaving a small gap between naming a related tool and full routing guidance.

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