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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely non-obvious behavior: a 'filter' group is re-matched on each use, and the site count reflects the current match, which matters for reasoning about freshness of the result.

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?

Information-dense but the opening is a fragment ('The agency's saved site groups, by name:') and the deeply nested parenthetical defining 'kind' is hard to parse on a first read. It could be restructured into short, front-loaded clauses without losing content.

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 carries the burden of describing the return shape, which it does (selection_id, kind, site count). It also points at the consuming tools, leaving only minor gaps such as ordering/formatting details.

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?

The tool takes zero parameters, so the baseline is 4. The description goes slightly further by explaining the semantics of the returned selection_id and how to consume it, though there are no inputs to disambiguate.

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 resource ('the agency's saved site groups') and enumerates exactly what each entry contains: selection_id, kind (sites vs filter), and current site count. An agent can distinguish this from list_sites and other siblings without opening any 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 routes the agent onward: pass a selection_id into fleet__list_sites filter or fleet__bulk_edit site_filter, and call fleet__list_sites to resolve actual sites. It also implies this is a prerequisite/discovery step, though it does not state any exclusion or 'when not to use' condition.

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