customer_add_purchase

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

No annotations are provided, so the description must carry the burden. It discloses that the link 'Takes priority over receipt validation links', which is a key behavioral trait. However, it does not mention side effects, required permissions, or reversibility. This is adequate but not comprehensive.

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 concise with five bullet points, each adding meaningful information. It is well-structured and front-loaded. However, it could be slightly more streamlined by combining some points.

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 simplicity of the tool (two required params, no output schema), the description covers the essential aspects: what it does, the format for purchaseId, the priority behavior, and required fields. It is complete enough for an agent to invoke correctly.

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?

The schema provides descriptions for both parameters, and the description adds value by specifying the format for purchaseId ('platform:purchaseId') and clarifying that customerId is the application username. This goes beyond the schema alone.

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 clearly states the tool's purpose: 'Manually associate a customer with a purchase' and 'Links a purchase to a specific customer'. It uses specific verbs and resources, and the function is distinct from sibling tools like purchase_get or purchase_list.

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?

The description provides guidance on when to use this tool: 'Takes priority over receipt validation links' and 'Useful for manual purchase management'. It also specifies the required format for purchaseId as 'platform:purchaseId'. While it doesn't explicitly state when not to use it, the context is clear.

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