start_timer

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

With no annotations, the description bears full responsibility. It discloses that the tool 'starts a timer' and 'creates a running time entry', indicating mutation. However, it does not describe side effects (e.g., if another timer is already running) or auth requirements, which are critical for a mutation tool.

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 description is extremely concise with one clear sentence that is front-loaded with the key action. No filler or unnecessary information.

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?

Despite having 5 parameters and no output schema, the description omits critical context: return value, error handling, what happens on duplicate timers, or how to stop the timer. For a tool with no annotations, this is insufficient.

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 high (80%), so the baseline is 3. The description adds no extra meaning beyond the schema's parameter descriptions. It does not explain how parameters like external_reference affect behavior or provide formatting hints.

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 clearly states the verb 'start' and resource 'timer for a new time entry', and distinguishes from sibling tools like restart_timer and stop_timer by specifying it creates a 'running time entry that tracks time automatically'.

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 use this tool versus alternatives. For example, it does not mention whether starting a new timer stops an existing one or what prerequisites are required (e.g., no overlapping timers). Implicit usage only.

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