Describe consumer group (with lag)

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

With no annotations provided, the description carries the full burden, but only reveals a read-like action ('describe') plus the aggregation detail ('per-partition and total lag'). It doesn't state behavior on nonexistent groups, whether broker-side offset fetching occurs, or what 'state' fields actually appear. It is non-destructive by wording but adds little safety/permission context beyond the annotation-free baseline.

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?

One sentence, front-loaded with the core purpose (state + lag) and entirely free of filler. It is appropriately sized for a single-parameter read tool and every word 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 tool with no output schema and no annotations, the description tells the agent what it computes (state, per-partition lag, total lag), which is the surface coverage expected. However, it leaves the shape of 'state' vague, gives no field directions, and offers no routing guidance to siblings — so an agent cannot predict the full return structure or the prerequisite (existing groupId) without inference.

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% since groupId is fully described as 'Consumer group id', so the baseline is 3. The description only reinforces the role by saying 'across its topics', adding no format, source, or units detail beyond the schema. It doesn't need to compensate further, but it doesn't add paramet-specific meaning either.

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 names a specific verb-resource pair ('describes a consumer group') and adds a unique deliverable — per-partition and total lag computed across its topics — which is exactly what separates it from the sibling list_consumer_groups. The title reinforces the scope with '(with lag)'. An agent reading this knows precisely what the tool returns that no other sibling provides.

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 mention of lag computation implies 'use this when you need lag or the detailed state of a specific group,' but no when/when-not guidance is given. There is no explicit statement like 'to enumerate groups first, use list_consumer_groups' or how to choose between this and topic_offsets. Usage context is visible only by implication.

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