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 covered. The description adds only that the fetch is by Id and scoped to a single record; it says nothing about not-found behavior, error handling, or what the returned object contains. With annotations carrying the safety burden, this is adequate but thin.

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 sentence that front-loads the operation and resource before the conditional qualifier. No filler, no repetition of the title.

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 single-record fetch this covers the essentials, and the annotations plus 100% schema coverage fill in the rest. It omits what happens when the Id does not resolve and how the company parameter interacts with multi-company connections, with no output schema to compensate.

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 the id and company parameters are already documented in the schema. The description's "by Id" merely restates the required parameter and adds no format or syntax guidance beyond it, so the baseline of 3 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?

States a specific verb (Get), resource (a single time activity), and system (QuickBooks Online), plus the lookup key (by Id). This distinguishes it from search_time_activities and update_time_activity without needing the schema, though it never names the sibling it is distinct from.

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?

"when no search or write answer already holds it" implies the tool is a fallback used only when a search result or a write response hasn't already supplied the record, which is implied usage rather than an explicit when/when-not rule. It does not tell the agent to prefer search_time_activities when the Id is unknown.

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