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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the tool is clearly a safe read. The description adds valuable context: that it accesses a 'trusted USD-cent price' from a 'configured merchant catalog' and explicitly rules out Stripe/checkout operations. No contradiction with 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?

The description is extremely concise: two sentences (20 words) that front-load the purpose and add a clarifying exclusion. No wasted words; every sentence earns its place.

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-only tool with one parameter and an existing output schema, the description covers all needed aspects: what it does, what it doesn't do, and where to get the parameter value. Additional details (like output structure) are unnecessary given the output schema. Complete enough for an agent.

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 description coverage is 100% for the sole parameter 'productId', and its schema description clearly states it is 'A stable ID returned by vibecart.list_products.' The tool description adds no further parameter details, but the schema already provides adequate guidance. Baseline 3 is appropriate.

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 explicitly states 'looks up one product and its trusted USD-cent price' from the catalog, which is a specific verb and resource. It clearly distinguishes from sibling tools like 'list_products' (returns multiple) and 'create_checkout' (creates a checkout) by stating what it does and doesn't do.

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?

The description tells when to use this tool (to look up a single product) and explicitly states what it does NOT do ('Does not access Stripe or create a checkout'), which helps avoid confusion with 'create_checkout'. However, it does not explicitly mention alternative tools or when not to use it, though that is implicit from sibling names.

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