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

Annotations already cover readOnly/non-destructive/closed-world, and the description adds substantive context beyond them: no input is taken, the id is opaque and stable across sign-ins and reconnections, an error with a sign-in prompt is returned when no account is linked. This is rich behavioral disclosure for a read tool.

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?

Front-loaded with purpose and tightly written, with each sentence carrying distinct information (purpose, input model, return semantics, error behavior, non-usage). Slightly long for a zero-param tool but nothing is padded.

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?

Covers purpose, input source, return shape and stability, error/sign-in behavior, and the scope where it is not needed. Output schema exists so return values needn't be enumerated; everything an agent needs to call and route correctly is present.

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?

Zero parameters, so the baseline is 4, but the description goes further by explaining that the account identity comes from the sign-in session rather than any argument. That meaningfully clarifies the input model beyond the empty schema.

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 verb (confirm) and resource (which teas.co.uk account is linked), and positions itself precisely against siblings like my_orders, my_subscriptions and rewards_balance. An agent can tell it apart from account-scoped tools without opening any schema.

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 names when to call it (before my_orders/my_subscriptions/rewards_balance, or when the customer asks which account they are signed in with) and when not to (searching, basket and checkout work without an account). Both the affirmative and exclusionary conditions are given.

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