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

With empty annotations, the description carries the full disclosure burden. It mentions the return format ('a json object, in the 'values' object') but does not disclose any behavioral aspects such as errors, permissions, pagination, or whether the customer must exist.

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?

The description is very brief, using a single sentence plus @param and @return annotations. It is concise and front-loaded, though the @return phrasing is somewhat awkward.

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 simple read tool with one parameter and an output schema, the description is minimally adequate. However, it lacks context on when this is preferred over similar tools like customer_get_invoices, and the return structure is only partially described.

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 schema provides customer_id as an integer with no description, but the description adds '@param customer_id: The customer's database id', clarifying it is the internal DB identifier. This adds meaningful context beyond the schema.

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 clearly states the tool 'Returns the customer's payment history', which specifies a verb and resource. It distinguishes from sibling tools like paywall__customer_get_invoices by naming 'payment history', although it does not explicitly contrast them.

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?

No guidance is provided on when to use this tool versus alternatives. There is no mention of contexts where payment history is needed or exclusions (e.g., when to use invoices instead).

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