start_timer

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

With no annotations provided, the description carries the burden of behavioral disclosure. It discloses one key behavior—the failure condition when another timer is running—but does not cover other aspects like success return values, permissions, or idempotency. This adds some context but lacks depth.

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 concise, consisting of two sentences with no filler. It front-loads the primary purpose and includes one critical behavioral note, making every word meaningful.

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?

The description covers the core purpose and failure condition, which is essential for a start_timer tool. However, since there is no output schema, it does not explain what happens on success (e.g., return value), and it does not reference related tools or prerequisites like checking the current timer. It is adequate but could be more complete.

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 input schema has 100% description coverage for all 3 parameters, so the schema already provides parameter semantics. The description adds no additional parameter details beyond mentioning 'project' and 'task,' which maps to existing schema fields. This aligns with the baseline score of 3 for high schema coverage.

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 the specific verb 'Start' and clearly identifies the resource as 'time tracking on a project and task.' This directly conveys the tool's action and distinguishes it from siblings like stop_timer, get_current_timer, and delete_time_entry.

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?

The description implies when to use the tool (to start tracking) and includes a precondition ('Will fail if another timer is already running'). However, it does not explicitly mention alternatives or suggest checking get_current_timer first, leaving the usage guidance mainly 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.