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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description's 'Get' aligns with those signals. The description adds the source system and ID-based lookup as context, but does not disclose return behavior or error handling. With annotations covering the safety profile, this is adequate but not enriched.

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 repetition. Every word contributes to identifying what the tool does and how it is invoked.

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?

This is a simple point-lookup tool with full schema coverage and read-only annotations, so the description is essentially complete for invocation. It does not describe the return object or not-found behavior, but for a straightforward get-by-ID operation with supporting annotations, the gap is minor.

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%, with both 'id' and 'company' already documented. The description only reinforces the 'by Id' retrieval concept already present in the schema, so it adds no new parameter-level meaning beyond the baseline.

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'), names the resource ('single time activity'), identifies the system ('QuickBooks Online'), and specifies the lookup key ('by Id'). It clearly distinguishes itself from search_time_activities by indicating point retrieval by identifier rather than searching or filtering.

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' gives clear context for when to use this tool: when the caller already has the QuickBooks TimeActivity ID. It does not explicitly name an alternative for searching, but the intended usage is clear and no misleading guidance is present.

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