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

readOnlyHint=true already tells the agent this is a safe, non-mutating read, and the description adds a useful mapping to the underlying GET /contact-groups endpoint plus the returned field set. It does not disclose pagination behavior or list size/rate considerations, which is the remaining gap.

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 compact clauses, front-loaded with purpose followed by returned content and the API mapping. No filler sentences and nothing repeated from the schema.

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 compensates well by enumerating the fields a contact group carries, so the agent knows what comes back. Only pagination/total-count behavior for a paged list is left unaddressed.

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% — page and limit are fully documented inline with ranges and default. The description adds no parameter detail, so the baseline of 3 for schema-driven params is correct.

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 (contact groups), then immediately defines what a contact group actually is — alert destinations with emails, mobile numbers, integration ids, and ping URL. No sibling tool covers contact groups, so the distinction from the get_/list_ check tools is unambiguous.

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?

Tells the agent the downstream purpose: the returned ids are meant to be plugged into a check's contact_groups field, which effectively tells you when to call this. It stops short of naming an alternative tool or stating exclusions, but for a leaf list endpoint there is no meaningful alternative to route against.

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