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

The description adds the useful nuance that this is a record-keeping/ingestion event rather than a payment-capture operation, which goes beyond the annotations' write flags. It does not, however, describe side effects or failure behavior; since the annotations already carry the core write semantics, the gap is moderate rather than severe.

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 substantive description is a single efficient sentence, front-loading the action and source. The only waste is repeating 'Create Charge' before that sentence, so it earns a 4 rather than a 5.

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?

Given the rich input schema, complete parameter descriptions, annotations, and an output schema, the description doesn't need to explain return values or parameter formats. It is complete enough for an agent to select and invoke the tool, though it omits deeper business rules such as whether the customer must already exist.

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 the input schema fully documents each parameter. The description adds no parameter-level meaning beyond the general 'revenue event' framing, which keeps it at the baseline for fully covered schemas.

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 uses a specific verb ('Record') and resource ('customer revenue event') and adds the source system ('external billing system'), which clearly communicates what createCharge does. It doesn't explicitly name sibling tools, but the create/delete/list charge sibling set is easily distinguished by the verb and domain.

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 phrase 'from an external billing system' provides clear context for when this tool is appropriate: ingesting revenue events that occurred outside the system. It doesn't give explicit exclusions or name alternative tools, but the context is specific enough to prevent confusion with customer creation or charge listing/deletion.

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