start_timer

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

No annotations exist, so the description carries the full burden of behavioral disclosure. It states that the timer starts immediately or at a given time today, but it doesn't disclose what happens if a timer is already active or other side effects.

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?

The action is front-loaded and the parameter list is compact, with each line adding distinct information. There is no filler or redundant explanation.

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?

It covers invocation basics and parameter semantics, and an output schema exists to describe return values. However, it doesn't address interaction with an already-running timer or how it relates to sibling timer tools, which is relevant for a state-changing tool.

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 schema has no per-parameter descriptions, so the Args list supplies the needed meaning for all four parameters. It clarifies that project/activity accept names or IDs, gives a format example for start ('09:00'), and notes the default behavior.

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 uses a specific verb-resource pair ('Start a running timer') and clarifies the optional start-time behavior. It doesn't explicitly distinguish from sibling tools like log_time or restart_timer, but the action is unambiguous.

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?

No guidance on when to prefer this over log_time, restart_timer, or active_timers. The description only defines the operation, not the selection context or exclusions.

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