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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds real behavioral value beyond that: cursor-based pagination mechanics, the { customers } response envelope, and the non-obvious API restriction that cursor requests accept only `limit`. It does not cover rate limits or ordering guarantees, keeping it below a 5.

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?

Front-loads the purpose, then pagination, then the critical cursor constraint flagged with IMPORTANT, then the endpoint. Dense but every sentence is useful, aside from the slightly redundant restatement of filter fields already implied by the schema.

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 correctly supplies the return shape ({ customers }) and cursor field names an agent needs to page. For a 9-parameter read tool this is nearly complete; error behavior and sort default are the only omissions.

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 schema already documents every parameter, including the cursor-alone rule and sort enum. The description restates the filterable fields and the limit default/max, which adds marginal reinforcement rather than new semantics. Baseline 3 is appropriate when the schema does the heavy lifting.

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 ('List customers') plus scope: optional filters and sorting, with the REST endpoint GET /customers named. This is clearly distinguishable from the single-resource sibling recharge_get_customer and from the other list_* tools by resource.

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 concrete when-to-use rules for the parameters (filter by email/ids/date ranges) and a strong operational constraint: on cursor requests, only `limit` may accompany `cursor`, all other filters must be omitted. It never explicitly names an alternative sibling (e.g., use recharge_get_customer for a single customer), so it falls short of a 5.

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