Start timer

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

With no annotations, the description carries the behavioral burden. It clearly identifies the main side effect of starting a new running timer and adds context about entry_method modes and existing-timer preference. It does not specify whether an already-running timer is stopped automatically, what the success response looks like, or what error/conflict behavior the caller should expect.

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 core action is front-loaded, and the description is compact without padding. The phrase 'When description.from is template' is slightly cryptic and the sentences are dense, but every sentence earns its place.

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 13-parameter, annotation-less mutation tool with no output schema, the description covers the important config and timing semantics but still leaves relevant gaps: the return value, automatic handling of a running timer, and explicit comparison to stopping or getting the current timer. This is adequate but not fully 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?

Input schema coverage is 100%, so the baseline is 3. The description adds genuine value beyond the schema by explaining entry_method's automated modes (include_seconds, start rounding, overlap) and by clarifying when issue_number/issue_title must be supplied for a description template. These details are not captured by the schema property descriptions alone.

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 opening sentence, 'Starts a new running timer,' uses a specific verb plus resource and clearly conveys the tool's core action. The word 'running' also helps distinguish it from entry-creation or timer-stopping siblings, though it never explicitly names a competing tool such as clockify_create_time_entry or clockify_stop_timer.

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 gives useful operational context: prefer stopping any existing timer first, conditionally pass issue_number/issue_title for templates, and pass config_root when the MCP is user-scoped. It does not explicitly say when to choose this tool over stop_timer, get_running_timer, or create_time_entry, so the selection guidance is mostly implied.

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