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

Annotations already mark the call read-only and non-destructive, and the description adds substantial behavioral guidance: pending means wait, failed should not be retried, chat acknowledgement is not proof of payment, and agent-link sessionId should be reused without re-running begin_agent_link. No annotation contradiction.

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 dense but every sentence earns its place: purpose and return format first, then usage triggers, then edge-case and authentication rules. There is no filler or tautology.

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?

Completes the picture despite a modest schema: return fields, trigger conditions, missing-id fallback, pending/failed handling, and auth/sessionId behavior are all present. An agent has everything needed to call this tool 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 covers sessionId in detail but leaves purchase_id undocumented, so the description compensates by tying purchase_id to list_purchases and to the post-create_purchase context. It also explains when to pass sessionId and warns against inventing one. Slightly generic on purchase_id format but adequate.

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?

States a specific action—get purchase status by ID—and names the returned fields (paid boolean and payment.status). This is clearly distinct from sibling tools like get_payment_status because it is anchored to purchases and includes a concrete return shape.

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?

Gives explicit triggers: call after create_purchase or when the user asks about order/payment/purchase status. It also prescribes the fallback of calling list_purchases first when purchase_id is missing, and tells the agent what to do for pending and failed outcomes.

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