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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description earns credit by disclosing the substance of the response — the customer's claim, the evidence that wins, typical origin situations, and a source link — which matters because no output schema exists. It omits what happens for an unrecognized code, a minor gap.

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 sentences, zero filler, with the capability stated first and the accepted input forms second. Every clause 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?

With only two fully documented parameters and no output schema, the description covers the essentials by describing what the returned explanation contains and which input shapes are valid. Only the error path for an unknown or malformed code is left unaddressed.

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%, so baseline would be 3, but the description adds real value by listing accepted formats beyond the schema's examples: numeric codes like 4853 and alphanumeric ones like C08, plus network-prefixed forms such as "Visa 10.4". That signals the code field tolerates embedded network identifiers, which the schema does not state.

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?

"Explains one chargeback reason code" gives a specific verb and a singular resource, and the enumerated payload (claimed reason, winning proof, typical situations, link) makes clear this is a detail lookup, not a listing. The word "one" implicitly separates it from list_reason_codes without needing to name it.

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?

Usage is only implied: an agent infers it should call this when it already holds a specific code and wants detail. There is no explicit statement about when to prefer list_reason_codes or get_help_with_a_dispute instead, and no prerequisites or exclusions are given.

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