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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered. The description adds only "single item ... by Id," with no information on auth/company scoping behavior, error behavior for missing Ids, or rate limits, so it adds limited value beyond the structured fields.

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?

A single front-loaded sentence with no filler: verb, resource, source system, identifier, and the usage condition all appear in order of importance.

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 two-parameter read tool with full schema coverage and complete read-only annotations, this is nearly sufficient. The only gap is the absence of any note on behavior when the Id does not resolve or on which company is used by default.

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 (id and company), so the schema carries the semantics. The description only restates that lookup is by Id, adding nothing about the optional company selector or Id format beyond what is already documented.

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?

States a specific verb and resource ("Get a single item from QuickBooks Online by Id") and distinguishes the single-fetch case from the search/write families of siblings. It never names search_items directly, so the differentiation is category-level rather than tool-level.

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?

Provides an explicit use condition: use this "when no search or write answer already holds it," which steers the agent away from re-fetching data it already has from search_items or a create/update response. It does not name the alternative tool or state an exclusion (e.g., batch retrieval), so it falls short of a 5.

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