start_timer

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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, and the description reinforces this by warning that every call creates a new timer. It adds genuinely new context beyond the annotations by specifying the rounding-up conversion and the requirement to preserve timer_id and min_seconds in task context and summaries.

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 tight sentences, front-loaded with the core action followed by the conversion rule and the deduplication/state rule. No filler, and each sentence carries a distinct instruction.

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?

An output schema exists, so return values need no explanation, and the description covers the remaining gaps: unit conversion, the non-idempotent create-a-new-timer behavior, and what state to carry forward. Nothing an agent needs to invoke this correctly is missing.

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 0% and the sole parameter min_seconds is only constrained by type, exclusiveMinimum 0 and a maximum. The description fully compensates by defining the unit (whole seconds), the rounding rule (round up) and a worked example (30 minutes = 1800).

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 gives a concrete verb+resource ('Start a timer') and qualifies the scope as the beginning of a task with a user-requested minimum duration, so an agent can immediately tell it apart from check_timer by the verb alone. It stops short of naming the sibling explicitly, which keeps it from a 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?

It states when to call (at the start of a task) and, unusually, a when-not rule: 'Each call creates a new timer; reuse the existing timer for the same task, including after status questions and context compaction.' The alternative tool check_timer is never named, so the routing guidance is implied rather than explicit.

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