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

Adds real behavioral context beyond the annotations: multiple concurrent timers are allowed, and the server clock is the default start time. However, annotations declare destructiveHint=true and idempotentHint=true, and the description never explains why starting a timer is destructive or how retries interact with request_id, leaving the most consequential hint unexplained.

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?

Three short sentences with zero waste, and the trigger condition is front-loaded ahead of the timestamp and concurrency details.

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 five-parameter mutation with no output schema, the description covers the trigger, default time source, and concurrency but omits the unexplained destructive flag and the required description parameter. An agent could call it correctly but would be guessing on those two points.

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 coverage is 60%, with request_id, started_at and business_id documented; client_id and description are not. The description reinforces client_id ('for work on a client') and started_at semantics, but says nothing about the required free-text description parameter, so it only partly compensates for the coverage gap.

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 and resource ('Start a timer for work on a client') with scope detail, so an agent can distinguish it from timer_stop and timers_list without opening the schema. It stops short of naming the sibling tools explicitly, so sibling differentiation is implicit rather than stated.

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?

Gives an explicit trigger ('when the user says they are starting') and a rule for the optional timestamp ('Otis's clock sets the start unless the user reports an earlier time'). It does not say when not to use it or point at an alternative such as timers_list or timer_stop.

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