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

With no annotations, the description must carry behavioral weight, and it discloses the fixed size of the result set (9 codes), the covered networks, and the shape of each entry (a one-line summary). It does not discuss permission needs or any dynamic behavior, but for a static, parameterless reference list there is little further behavior to disclose.

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, no filler; the enumeration scope is front-loaded and the usage cue follows. Every clause adds information an agent can act on.

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 parameterless reference list with no output schema, the description conveys enough about the return content (9 entries, one-line summaries, three networks) to call the tool and interpret results. A note on what a caller should do with the output (e.g. feed a code into lookup_reason_code) would close the remaining gap.

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 tool takes zero parameters, which is the baseline-4 case under the rubric. The description's mention of the three covered networks also clarifies that no filtering argument is needed or accepted.

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?

Specific verb (List) plus a precisely scoped resource: the 9 card-network chargeback reason codes, naming the networks (Visa, Mastercard, Amex) and the return format (one-line summaries). That scope makes it clearly distinct from lookup_reason_code, which returns a single code.

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?

"Use first when the user mentions a chargeback without a code" gives an explicit triggering condition and implicitly defines when not to use it (code already known). It never names lookup_reason_code as the alternative, so the routing is inferred rather than stated.

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