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

Annotations already establish the tool as read-only, idempotent, and non-destructive, so the description's burden is lower. It adds useful behavioral context beyond annotations: the default date range is the current week in the workspace timezone, and results include resolved names and per-entry rates. It does not mention pagination limits or cursor behavior, but those are captured in the schema.

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?

Four sentences, each earning its place: when to use, what it returns, when to use the alternative, and what not to use it for. The most actionable usage trigger is front-loaded, and there is no filler or repetition.

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?

The description covers usage scenarios, output content, defaults, and sibling routing. With no output schema, mentioning that it returns individual entries with resolved project/client names and per-entry rates is helpful. Minor gaps remain around pagination and the exact meaning of billable_only, but those are reasonably inferable from the schema and sibling context.

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 high at 88%, so the description does not need to explain each parameter. It references project/client as useful dimensions but adds no detail beyond the schema. The description's mention of date defaults aligns with start_date/end_date defaults already declared in the schema.

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 and resource ('list time entries') and clearly states what the tool returns: individual entries with resolved project/client names and per-entry rates. It also distinguishes itself from time.report by naming that tool for totals and breakdowns, and explicitly excludes calendar events, tasks, and reminders.

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 description opens with concrete trigger scenarios ('asks what they worked on, what they logged, or wants entries for a day, week, project, or client'). It names the alternative tool for a different use case ('For totals and breakdowns use time.report instead') and gives negative guidance ('Do not use for calendar events, tasks, or reminders').

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