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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is fully covered by structured data. The description adds only one behavioral detail (running timers return elapsed minutes); it says nothing about pagination, default result size, or what filtered results look like.

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?

Two short sentences with no filler, and the listing scope is front-loaded. The phrasing 'running ones with their elapsed minutes' is slightly clipped but readable.

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?

A five-parameter list tool with no output schema and 20% schema coverage needs the description to explain filtering, pagination, and return shape. The description covers none of these, leaving significant gaps for correct invocation.

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 only 20% — just business_id is documented. The description adds no meaning for limit, offset, state, or client_id, so an agent gets no guidance on the four undocumented parameters.

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+resource ('List timers') and adds scope detail that running timers include elapsed minutes. It is clearly distinct from timer_start/timer_stop, though it never names those siblings explicitly.

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?

'Check for running timers before starting another for the same work' gives a concrete use condition tied to timer_start. It stops short of stating exclusions or naming the alternative tool explicitly.

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