time_stop_timer

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

With no annotations, the description carries the full burden and does disclose meaningful behavior: a conditional side effect (adding a charge line item to the ticket) and a specific error condition (422 when already stopped). It omits permissions/auth requirements and whether the stop is reversible, so it stops short of a 5.

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 sentences, each load-bearing: core action first, conditional side effect second, error behavior last. No repetition of the name or schema content.

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 one-parameter mutation with no output schema, the description covers the action, the conditional billing side effect, the fallback tool, and the failure mode. It lacks auth/permission or idempotency notes, but nothing essential to calling it correctly is missing.

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?

Single parameter with 100% schema description coverage, so the schema already defines 'id'. The description adds genuine meaning by tying that same ID to the follow-up tickets_charge_timer call (timer_entry_id = this timer's ID), which is beyond the schema.

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 ('Stop a ... timer') and clarifies scope by explicitly covering both the running and paused states. It is clearly distinguishable from the adjacent time_start_timer and time_pause_timer siblings in the same family.

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?

Explicitly names the alternative path: if 'charge timers by default' is off, the agent must call tickets_charge_timer with timer_entry_id set to this timer's ID. That is a concrete when-to-use-vs-alternative instruction rather than vague context.

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