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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds value beyond that by disclosing the underlying GET path, the shape of the reply, and the performance/size tradeoff of expand_lines — a genuinely useful behavioral note for an agent deciding whether to expand.

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 scope and resource, followed by the one decision-worthy caveat and the endpoint. Nothing is wasted and nothing important is buried.

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 helpfully names the returned fields (id, status, next billing date) and the size implication of expand_lines, and pagination is fully covered by the limit/cursor schema descriptions. It is close to complete for a read-only list tool; only the pagination flow isn't echoed in prose.

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%, so customer_id, limit, and cursor are fully documented already. The description's only parameter note on expand_lines largely restates the schema's own 'Include the subscription lines (larger reply). Default false,' so it adds little beyond structured data — baseline 3.

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 and resource with explicit scope ('one customer's subscriptions') and even enumerates returned fields, which lets an agent distinguish it from the plural awtomic_list_subscriptions and from the single-resource awtomic_get_subscription. It stops short of naming those siblings explicitly, so the differentiation is implicit rather than stated.

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?

Gives conditional guidance for expand_lines (set it to include lines, at the cost of a much larger reply), which is real usage advice. However, there is no when-to-use/when-not framing relative to awtomic_list_subscriptions or awtomic_get_subscription, and pagination behavior is left to the schema.

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