Attach an external-observation timer to a specific target and section to track timing without reading screen pixels or canceling input.
Attach an external-observation timer to an explicit target and section; never reads screen pixels or cancels input.
| Name | Required | Description | Default |
|---|---|---|---|
| timer_id | No | ||
| target_id | Yes | ||
| section_id | Yes |
Changes observed during successful MCP inspections.
v0.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true and idempotentHint=false, so the threshold is lower, and the description adds real context by scoping out screen-pixel reads and input cancellation. However, it never says what the destructive part actually is — whether an existing attachment is overwritten, or what happens on repeated calls — which is exactly the gap the destructive hint leaves open.
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?
One tight sentence with the action front-loaded and no filler. The trailing negative clause is useful but compressed to the point of ambiguity about what it is contrasting against.
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 destructive, non-idempotent mutation with zero schema documentation and no output schema, the description should cover the effect on existing state, the optional timer_id, and what a caller gets back. It covers only the bare action, so an agent could call it correctly-shaped but not predict its consequences.
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 description coverage is 0% with three undeclared parameters. The description names the two required concepts (target, section) but says nothing about their meaning, format, or relationship, and the optional timer_id is completely undocumented in both schema and description.
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+resource ('attach an external-observation timer') and the two anchors ('explicit target and section'), which cleanly separates it from timer_detach/timer_prepare. It does not name the sibling alternative or explain how it relates to prepare/calibrate, so it stops short of full differentiation.
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 when-to-use or when-not-to-use guidance beyond the words 'explicit target and section'. With siblings timer_prepare, timer_calibrate, timer_status and timer_detach present, the agent gets no signal about ordering or prerequisites (e.g., must the timer be prepared first?).
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.