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

Annotations already provide the safety profile (readOnlyHint=true, destructiveHint=false). The description adds useful scope information — that it returns exactly one vendor selected by Id — which is consistent with the annotations. However, it does not disclose additional behavioral traits such as not-found behavior, rate limits, or return format, though for a simple read operation this is acceptable.

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 a single, front-loaded sentence with no filler. It conveys the action, target system, and identifier in a compact way that is easy for an agent to parse quickly.

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 read-only operation with only two parameters, one required, the description plus schema and annotations are sufficient for an agent to invoke the tool correctly. The only minor gap is that no output schema exists and the description does not hint at the structure of the returned vendor object, but this is a small omission for such a simple retrieve-by-id tool.

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%, as both 'id' and 'company' have clear textual descriptions in the input schema. The description only echoes 'by Id' and adds no extra meaning beyond what the schema already provides, so the baseline score applies.

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?

Description uses the specific verb 'Get', names the resource 'a single vendor from QuickBooks Online', and the access method 'by Id'. This clearly distinguishes it from search/list tools like search_vendors and from vendor report tools such as get_vendor_expenses, so an agent can tell exactly what it does.

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 'by Id' phrasing implies that this tool should be used when a specific vendor Id is known, and the required 'id' parameter confirms this. However, the description does not explicitly mention alternatives like search_vendors when no Id is available, nor does it state exclusion criteria. Usage is inferred rather than spelled out.

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