start_timer

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

With no annotations, the description carries the full burden, and it does disclose one important trait: the time is not logged on start but on stop_timer. It does not say whether starting a second timer stops or duplicates the first, whether the timer is per-user or per-issue, or what the call returns.

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 short sentences, front-loaded with the action, then the trigger, then the downstream effect. Every sentence carries distinct information and none restates the tool name or title.

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 two-parameter tool with no output schema and no annotations, this covers purpose, timing, and the side effect that matters. The remaining gap is edge-case behavior — repeated starts and error handling for an invalid issue_id — which a longer description could have covered.

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 100%, with issue_id and description both documented inline, so the baseline of 3 applies. The description adds no parameter-level meaning beyond the schema — it never mentions that issue_id refers to a Redmine issue or how the description text surfaces in the time entry.

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?

States a specific verb and resource ("Start a timer for an issue") and immediately frames it against the sibling stop_timer, which is what actually logs the time. An agent can tell what this does and how it pairs with the rest of the timer trio without opening the schema.

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?

"Call this when you BEGIN working on a task" gives an explicit trigger condition, and naming stop_timer clarifies the expected lifecycle. It stops short of exclusions — nothing says what to do if a timer is already running or when cancel_timer should be used instead.

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