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

The description adds substantial behavioral context beyond the annotations: accepted formats, base64 plus filename delivery, authorization rules, the 10-per-expense limit, and plan-based size caps. It does not explain the destructiveHint=true implication, such as whether the addition modifies or replaces existing receipt state or how it can be undone.

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?

The description is compact and front-loaded: attachment behavior comes first, followed by permissions and limits. Every sentence contributes operational detail without repetition.

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?

Given the three required parameters, annotations, and lack of an output schema, the description supplies enough context to invoke the tool correctly. It covers formats, encoding, authorization, per-expense count limits, and size caps.

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 parameter meaning is already largely documented. The description still adds useful semantics: accepted file types, the base64-encoded file plus filename convention, and file-size constraints that apply to the content parameter.

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?

The description states a specific verb and resource: attaches a receipt to an expense. It immediately distinguishes the operation from general attachment or expense-creation siblings by naming the exact target and supported receipt formats.

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?

It clearly states who may use the tool and that receipts can also be added to expenses already on an invoice. It does not explicitly name when to use this instead of add_attachment or delete_expense_receipt, so alternative routing is only implied.

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