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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safe read-only nature is covered. The description adds that it operates on QuickBooks Online and returns a single bill, but it does not disclose not-found behavior, authorization needs, or whether the full bill object is returned.

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 or redundant qualifiers. Every word contributes to identifying the tool's action, target, and criteria.

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 two-parameter getter with 100% schema coverage and safety annotations, the description is largely sufficient. It does not explicitly describe the return value or error cases, but the tool's name and 'Get a single bill' make the primary outcome evident.

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% for both parameters, with clear descriptions for 'id' and 'company'. The description adds no new parameter-level meaning beyond reiterating the Id-based lookup, so the schema carries the burden.

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 uses a specific verb ('Get'), a specific resource ('a single bill'), and a precise retrieval key ('by Id'). This clearly distinguishes it from sibling tools like search_bills, which perform broader lookups, and get_bill_payment, which targets a different entity.

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 phrase 'by Id' implies this tool is for retrieving a known specific bill, but the description does not explicitly say when to use it versus search_bills or other getters. There is no explicit guidance about what to do when the Id is unknown or which company must be specified.

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