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

The readOnlyHint annotation already declares this is a safe read, so the description needn't restate that. It adds one useful piece of context — the response includes line items — but with no output schema, it does not describe what happens when the id doesn't exist, what fields the credit note carries, or whether related records are expanded.

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?

A single short sentence with no filler, front-loading the cardinality ('one') and the lookup key ('by id'). The only weakness is that it is a fragment terse enough to border on under-specification rather than elegance.

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 one-parameter read tool with annotation-supplied safety and a fully documented schema, the definition covers the essentials plus the notable detail that line items are returned. Only edge-case behavior (not-found id) is absent, which is minor at this complexity.

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% and the single parameter is fully documented as a GUID with a pattern, so the schema does the work. The description only echoes 'by id' and adds no meaning beyond the schema, which is the expected baseline for a one-parameter tool.

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 resource and scope: a single credit note fetched by id, plus the fact that line items are included. This implicitly separates it from bokio_list_credit_notes, though it never names that sibling. Clear enough for an agent to know it retrieves one record rather than a collection.

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?

'One credit note by id' implies single-record lookup, which indirectly signals when to use it versus the list tool, but there is no explicit when-to-use guidance, no prerequisites, and no mention of how to obtain the id (e.g., from list_credit_notes). Usage 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.