start_my_clock

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

Annotations already declare readOnlyHint=false, idempotentHint=false, openWorldHint=true and destructiveHint=false, so the mutation/non-idempotent profile is covered. The description adds only the 'authenticated user' scoping (the clock belongs to the caller, not an arbitrary user), but says nothing about what happens if a clock is already running 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?

One front-loaded purpose sentence followed by a compact args list; no filler or redundant prose. The args block repeats parameter names from the schema, but each line still adds a small amount of semantics.

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 mutation tool with no output schema, the definition covers the essentials (purpose, scope, all params) and annotations carry the safety profile. It leaves gaps around preconditions (existing running clock) and failure behavior, which an agent starting a timer would plausibly need.

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%, so the description carries the full burden and largely meets it: it documents all five parameters and adds the non-obvious encoding 'billable (1) or not (0)', which the bare integer schema does not convey. The remaining parameter notes are terse and mostly restate the names.

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 states a specific verb and resource ('Start the clock') and scopes it to the authenticated user, which clearly separates it from sibling stop_my_clock and get_my_clock by name. It stops short of explicitly naming the alternative tools or contrasting with them, so it earns a 4 rather than a 5.

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 no when-to-use guidance, no prerequisites, and never mentions the sibling stop_my_clock or get_my_clock that an agent would choose between. The only signal is the tool name itself, which is implied rather than stated.

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