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

readOnlyHint=true already tells the agent this is a safe read with no side effects. The description adds only the raw upstream endpoint (GET /credit_notes) and no behavioral context such as pagination expectations, result ordering, or empty-result semantics, so it contributes little beyond the annotation.

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?

Three short sentences, front-loaded with the action and the filter before the endpoint detail. Nothing is bloated, though the raw "Chargebee API: GET /credit_notes" line is arguably noise for an agent that already has the tool contract.

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 paginated read tool with full schema documentation and a readOnlyHint annotation, and no output schema to explain, the definition covers what is needed. The remaining gap is behavioral expectation around pagination/ordering, which is minor.

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%, with limit, offset, and customer_id each fully documented including the Chargebee max of 100 and the customer_id[is] mapping. The description's "Filter by customer" merely restates customer_id, so baseline 3 is correct.

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 credit notes") plus the supported filter, which is enough to distinguish it from list_invoices, list_transactions, and other list siblings by resource alone. No explicit sibling call-out, which keeps it at 4 rather than 5.

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?

"Filter by customer" implies the primary use case (retrieving credit notes, optionally scoped to one customer), but there is no when-to-use/when-not-to-use guidance, no mention of alternatives for related lookups (e.g., get_invoice), and no note on when the customer filter is required.

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