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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety does not need repeating. The description adds the useful empty-state caveat ('if any') and lists the returned fields, though it does not describe response structure or error behavior in detail.

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 front-loaded sentence with no wasted wording. The key resource and scope are stated immediately.

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 no-parameter, read-only timer lookup with no output schema, the description is largely complete: it states what is shown, what fields are included, and that no timer may exist. It could be slightly stronger by clarifying the return shape when no timer is active.

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?

There are zero parameters, so parameter semantics baseline is 4. The description correctly adds no parameter detail because none are needed, and instead documents output fields.

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 ('Show') and resource ('running timer') and names the returned fields (project, task, start time). It is clearly distinct from start/stop timer siblings in practice, but it does not explicitly differentiate itself from them, so it falls short of 5.

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: call this to check whether a timer is currently running. The phrase 'if any' hints at the empty case, but there is no explicit guidance on when to use this versus get_my_time_entries, start_timer, stop_timer, or discard_timer.

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