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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows it's safe. The description adds substantial behavioral context: it specifies how to interpret return policies (negative days = 'Exchange only |X| days'), mandates display of specs table, and defines link-return behavior (base link during browsing, checkout link only after size finalization). This goes beyond the annotations and enriches agent 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 front-loaded with the core purpose in one sentence, followed by a clearly labeled 'MANDATORY AGENT INSTRUCTIONS' section with three concise bullet points. While it is longer than minimal, the content is relevant and structured. Each instruction earns its place, though it could be tightened slightly.

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?

An output schema exists, so return structure is covered elsewhere. The description fills in presentation rules, link formats, and policy interpretation, which the schema does not convey. It covers what data to expect and how to handle it, leaving few gaps for an agent to call this tool correctly. Missing edge cases (e.g., out-of-stock handling) are likely in the output schema.

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%, so all three parameters (handle, size_index, desired_size) are documented in the schema. The description mentions size_index in the link format but does not add new semantic meaning beyond the schema. Baseline 3 is appropriate when the schema fully covers parameter meaning.

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 opens with a specific verb 'Verify' and enumerates the exact resources (stock availability, live pricing, product specs, shipping/return policies, available sizes). It clearly distinguishes from siblings like products.items.get_by_handle by emphasizing 'live' data and sizing, which other tools likely lack. The purpose is unambiguous and scoped.

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 implies real-time checking but never explicitly states when to choose this over alternatives, nor does it mention sibling tools or exclusion conditions. It gives 'MANDATORY AGENT INSTRUCTIONS' about how to present results, but not when to invoke this tool vs. get_by_handle or search tools. The guidance is inferred rather than stated.

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