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

Annotations only declare the generic write profile (readOnlyHint=false, idempotentHint=false). The description adds the non-obvious behavior an agent must know: single concurrent timer, refusal-with-incumbent on conflict, a 24-hour cap, and that nothing is logged until the timer is stopped.

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?

Six short sentences, each carrying distinct information (scope, identifier forms, concurrency rule, duration limit, logging behavior, example utterance), with the core action front-loaded. No filler.

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?

With an output schema present, return values need not be explained, and the description covers the stateful constraints (concurrency, 24h cap, no logging until stop) that an agent needs before invoking a non-idempotent write with no required parameters.

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 100%, so projectId/project dual-mode, exact-code-first matching, ambiguity handling and the optional description are already documented in the schema; the description largely restates them plus the 'RISE' example. Baseline 3 applies since the schema does the heavy lifting.

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?

Specific verb ('Starts') plus resource ('a timer') plus actor ('the signed-in person') and the target scope (project/task/activity). It is clearly distinguishable from stop_timer, cancel_timer and list_running_timer siblings without opening any 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?

It gives real invocation conditions: one timer at a time, the call is refused while another runs, and the running timer is returned. It also supplies an utterance example ('start a timer on RISE for the site survey'), which tells the agent what kind of phrasing this tool serves. It stops short of explicitly routing to stop_timer/cancel_timer as the follow-up tools.

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