get_subscription_line_items

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

With no annotations, the description carries the burden of behavioral disclosure. It does explain the required input and return value, but it does not explicitly state whether the operation is read-only, mention authorization requirements, or describe error conditions. The 'Get' and 'Returns' phrasing implies a safe read, but this is not as explicit as it could be.

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 two concise sentences with no fluff. It front-loads the primary purpose and immediately adds the key prerequisite and return information, making every sentence valuable.

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 one-parameter getter with no output schema, the description covers the essential aspects: purpose, required input, sourcing instructions, and return values. It lacks only explicit notes on edge cases like empty results or authentication, but these are not critical for basic usage.

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 0%, so the description must compensate, and it does. It explains that subscriptionId is the subscription's internal FastSpring ID and tells the agent exactly where to obtain it (the 'id' field from get_subscription results). This provides meaningful semantics beyond the raw schema, though it does not detail the ID format.

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 uses a specific verb ('Get') and clearly identifies the resource ('products and quantities on a subscription'), distinguishing it from sibling tools like get_subscription. It further clarifies the return content as products, quantities, and SKUs, leaving no ambiguity about its purpose.

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 gives clear context by stating it requires the subscription's internal FastSpring ID, referencing the 'id' field from get_subscription results. This implicitly tells the agent to first call get_subscription, but it does not explicitly name alternative tools or exclusions, so it falls just short of a 5.

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