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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety and read-only profile is fully covered. The description adds one genuinely useful trait beyond the annotations — that each fact carries its source URL — but says nothing else about behavior or output shape. With strong annotation coverage, a 3 is appropriate.

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?

One efficient, front-loaded sentence with no waste; the returned fact categories are listed first and the source-URL note appended compactly.

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 the description need not explain return values, and it adequately conveys what is fetched for a simple one-argument lookup. The only shortfall is the unexplained merchant-identifier format, which leaves a small gap for a tool this simple.

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 0% for the single 'merchant' parameter, and the description only says 'of one merchant' without clarifying whether the value is an ID, slug, or name. The description does not compensate for the gap.

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 names a specific resource (one merchant's shipping, processing, returns, payment, and identity facts), so an agent knows exactly what data it retrieves. It lacks an explicit verb (the name 'get_' carries that) and does not explicitly contrast itself with siblings like get_product or list_merchants. Still clearly distinguishable as a single-merchant policy lookup.

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?

There is no when-to-use guidance: nothing says whether this is for policy questions vs. catalog lookups, nor when to prefer it over get_product or list_merchants. The agent must infer the use case from the noun list alone.

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