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

Annotations already establish readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds useful beyond-annotation context: owner-only access, the specific returned fields (person, task, day, minutes, rate in cents), and a note that expense descriptions and task titles are user-typed text.

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 front-loaded with the core purpose, then adds only the necessary access and data-provenance details. It is dense but appropriately sized, with no wasted sentences.

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 list tool with no output schema, the description adequately explains what is returned, including important field units and a caution about user-typed text. It does not describe pagination or ordering behavior, but the essential call semantics are covered.

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 all three parameters and both optional date filters documented in the schema itself. The description does not add syntax, format, or filtering semantics beyond what the schema already provides, 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?

The description states a specific verb and resource — what a project can still bill — and enumerates the two returned categories: finished billable time entries and billable expenses not yet invoiced. This distinguishes it from general listing siblings such as list_time_entries or list_expenses and from invoice-preview/creation tools.

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?

Usage is implied by 'what a project could still bill,' and there is a clear access precondition ('Only the project owner'). However, it does not explicitly say when to choose this over preview_invoice_from_work, create_invoice_from_work, or the other list_* siblings, so routing guidance remains incomplete.

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