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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is covered. The description adds genuine content beyond that by enumerating what state is reported (active entry, elapsed duration, today's aggregate). It stops short of saying what happens when nothing is tracked, which is the one behavioral question left open.

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, front-loaded with the live-state question and then the two quantities reported. Every clause carries information and nothing is repeated from the title or annotations.

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?

With an output schema present and full annotation coverage, the description only needs to frame the read — which it does. The minor gap is the empty-state behavior (no timer running), which an agent must infer from the output schema rather than the prose.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline is 4. No parameter claims are made or needed.

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 names the resource precisely — the currently running entry, its elapsed time, and today's running total — which is clearly distinct from get_summary, get_weekly_review, and list_time_entries. It reads as a list of return fields rather than an explicit verb+resource statement, so it leans on the name and title to establish that this is a read.

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?

"Right now" implies the use case (checking a live timer rather than history), but the description never states when to prefer this over get_summary or list_time_entries, nor what it returns when no timer is running. Usage is inferable but not spelled out or bounded.

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