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

Goes well beyond the readOnly/idempotent annotations by disclosing that prices and stock are re-read on every call, that a basket is retained 35 days after its last change, and that an unknown or never-filled basket returns an empty result rather than an error. These are exactly the freshness and edge-case behaviors an agent needs and cannot get from annotations.

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-loads what the tool returns, then layers behavior (refetch, retention, empty-result semantics), then closes with sibling routing. Each sentence carries distinct information with no padding.

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?

With an output schema present, return values need not be explained, and everything else an agent needs — freshness, retention window, empty-result behavior, and alternative tools — is covered. Nothing material is missing.

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% with a single optional parameter, and the description's guidance on basket_id ('only for hosts that do not identify the customer, pass the one an earlier basket tool returned') largely restates the schema's own parameter description. Baseline 3 applies since the schema already carries the 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?

States a specific verb (view/show) and resource (the customer's teas.co.uk basket), and names the concrete contents returned: live subtotal and delivery estimate. It is immediately distinguishable from add_to_basket, update_basket and checkout_link, which are named as the mutating siblings.

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 says when to use it (to show basket contents) and routes each adjacent action to its own tool: add_to_basket for adding, update_basket for quantities, checkout_link for paying. It also states the condition under which basket_id must be supplied versus omitted.

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