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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, yet the description still adds real value: the API is a preview surface that may change without a version bump, and it names the required OAuth scope. Both facts go beyond annotations and affect whether an agent should depend on the response.

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?

Two short sentences, front-loaded with the most decision-relevant fact ("Preview API") and the auth requirement. Nearly every clause earns its place; the fragment "their add-on marker" is terse to the point of being cryptic but costs little space.

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 3-param read tool with no output schema, the description covers stability and auth but omits pagination behavior despite the presence of limit/after, and never defines what a service group or "add-on marker" actually is. An agent can fire the call but cannot reason about the results or pagination strategy.

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 only 33%: locationId (required) and limit are completely undocumented in the schema, and the description says nothing about any of the three parameters. Worse, the one documented param (after) carries boilerplate text about stock movements that is misleading in this context, so nothing compensates for the coverage gap.

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 the returned resource ("Service headings and their add-on marker"), which tells an agent roughly what data comes back, but it never states a verb and gives no clue how a "service group" differs from the sibling list_services or list_resource_services. The agent must infer that this is a list operation over some grouping layer.

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 gives one concrete usability constraint — "Requires services:read" — which is genuinely helpful pre-call context, but it offers no when-to-use/when-not guidance and never routes the agent away from the many sibling list_* tools. Selection must be inferred from the name alone.

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