Retrieve one subscription

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

With no annotations provided, the description carries the full burden. It explicitly declares 'Read-only', which is a critical safety cue. It also discloses the resolution logic (default to current subscription if subscription_id omitted) and that it returns state/dates/Features. It does not mention error behavior or what happens if no subscription exists, but for a simple read this is adequate.

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 three sentences and front-loads the purpose and read-only note before diving into parameter logic. Each sentence adds value: purpose, access constraint, and alternative. Slightly wordy in the second sentence but acceptable and well-structured.

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 read tool with three parameters and no output schema, the description covers the core behaviors: what it returns, how to address a specific subscription, and the default behavior. It lacks explicit error handling notes and a detailed return format, but given the simplicity and the sibling pointer, it is sufficiently complete for an agent to call 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?

Schema coverage is 100%, so the schema already documents all three parameters. The description adds meaningful context: it explains why customer_ref is required (access path), what subscription_id does when omitted (default to current), and what offer_ref narrows to. This goes beyond the schema's bare descriptions and clarifies usage semantics.

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 ('Retrieves') and names the resource ('one ProAbono subscription of a customer'), plus the fields it returns (state, dates, Features). It clearly distinguishes itself from the sibling list_subscriptions by explaining the singular retrieval scope and the customer-based access path.

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?

Explicitly explains when to use this tool: it is the only way to retrieve a subscription (no retrieve-by-identifier), requires customer_ref, and explains the optional subscription_id and offer_ref parameters. It also directs the user to list_subscriptions for seeing all, giving a clear alternative.

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