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

Annotations already cover the safety profile (readOnlyHint, destructiveHint=false), so the bar is lower. The description adds genuinely non-structured behavior: one lookup is spent per vendor that is answered, and unmatched names are free — billing/rate semantics an agent cannot infer from annotations. It is consistent with idempotentHint=false, since repeats would incur further cost.

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?

Two short sentences, front-loaded with what the tool does, followed by the cost model. Every clause carries information; nothing is padding.

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 single-parameter read tool with full schema coverage and annotations covering safety, the description plus schema is nearly sufficient; 'one profile each' hints at the return shape even without an output schema. A note on what happens when a name and domain disagree, or on ordering of results, would close the last gap.

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 both name and domain fields are already fully documented, including the maxLength and maxItems constraints. The description's 'names, domains or both' and 'up to 25' restate the schema rather than adding format or resolution rules.

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 a specific verb (check) and resource (a list of vendors), plus the batch limit and the output (one profile each). It is clearly distinguishable from single-lookup siblings like find_vendor, though it never names them explicitly.

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 batch shape and the cost model imply this is the tool for checking many vendors at once, which is usable guidance. But it never says when to prefer it over find_vendor or get_vendor_profile, nor states prerequisites or exclusions.

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