fiken_add_purchase_attachment

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

The annotation readOnlyHint: false already indicates a write operation, and the description confirms it creates/adds. However, no additional behavioral context is provided (e.g., side effects, required permissions, or whether it replaces existing attachments).

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 a single sentence with no fluff, but it is under-specified. It sacrifices clarity for brevity, making it minimally acceptable in terms of conciseness.

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 lack of parameters, no output schema, and no explanation of how to provide the attachment data, the description is severely incomplete. An agent would be unable to use this tool correctly based solely on this definition.

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?

With zero parameters in the schema, the description should clarify how the purchase identifier and file content are communicated (e.g., via URL path or request body). It fails to do so, leaving the agent without essential information.

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 'Creates and adds a new attachment to a purchase' states the action but omits critical details such as how to identify the purchase or provide the attachment content. With no parameters in the schema, the agent cannot determine how to invoke the tool correctly.

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?

No guidance is provided on when to use this tool versus alternatives like fiken_get_purchase_attachments or fiken_create_purchase. There is no mention of prerequisites (e.g., requiring an existing purchase ID) or when not to use it.

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