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

The annotations already declare readOnlyHint, idempotentHint, and destructiveHint, and the description reinforces these with 'Read-only' and 'No purchase or mutation occurs,' which adds a small amount of context beyond the annotations. However, it does not mention potential errors, rate limits, or other side effects that might affect caller behavior.

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 two sentences long, starts with the core purpose ('Read-only identifier lookup'), and packs all necessary guidance without fluff. It front-loads the action and resource, then provides usage and alternatives in a compact, scannable manner.

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 identifier lookup tool, the description provides sufficient context: it explains what data is returned (price, availability, machine endpoint data), when to use it, and how it differs from siblings. It does not describe the output schema, but the presence of an output schema (as indicated in context) means that is not required. The description is slightly generic about optional parameters but still gives a complete picture 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?

The input schema provides descriptions for all parameters (ids, context, filters, signals, attribution), achieving 100% coverage. The tool description does not add much beyond what the schema states; it repeats the types of identifiers and mentions the return intent, but does not clarify the meaning or purpose of the optional parameters. Since coverage is high, a baseline of 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 clearly states the verb ('lookup') and resource ('catalog'), and specifies the exact use case: retrieving current price, availability, or machine endpoint data for known product, variant, SKU, or handle IDs. It also names sibling tools directly, distinguishing itself from search_catalog (unknown IDs) and get_product (single item full detail).

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 explicitly tells when to use this tool: 'Call this when you already have one or more product, variant, SKU, or handle IDs and need current price, availability, or machine endpoint data.' It also gives clear alternative instructions: 'Use search_catalog if IDs are unknown; use get_product for full detail on one selected item.' This leaves no ambiguity.

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