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

Beyond the annotations, the description adds key behaviors: the link sets quantities rather than adds, is idempotent (clicking twice gives same result), stock is re-checked with potential quantity reduction or row skipping, and checkout requires customer account. This goes well beyond the annotation flags and provides rich operational detail.

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 lengthy but well-structured into Args, Returns, Errors, and Notes sections. Each sentence adds value, though there is slight redundancy with annotations (e.g., 'writes nothing'). It could be tighter, but the organization aids readability.

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?

Given the tool's complexity, the description covers purpose, parameters, return format, error handling, and nuanced behaviors (idempotency, stock re-check, checkout auth). With an output schema and annotations present, the description provides comprehensive guidance for an agent to select and invoke the 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?

Even though schema coverage is 100%, the description adds crucial semantics: repeated product_ids are merged with quantities summed, unknown fields are rejected, explicit ranges for items and quantity, and the effect of the checkout flag. This adds meaning beyond the raw schema and helps the agent construct valid inputs.

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 states 'Build a link that puts the given products into the customer's cart' – a specific verb+resource that clearly distinguishes it from sibling query tools. It also clarifies the tool writes nothing and returns a URL, leaving no ambiguity about its function.

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?

Provides clear context: 'Give the URL to the customer and let them click it.' Implicitly distinguishes from sibling tools (which are for querying) but doesn't explicitly state when not to use or name alternatives. The use case is evident, though not exhaustive.

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