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

Beyond the single readOnlyHint=false annotation, it discloses that this writes stored state, is not safe to repeat blindly, that the public record exposes the interval plus a coarse bucket (never yet / 2 hours / day / week / longer) and never a timestamp, and that undeclared citizens are not measured. This is exactly the mutation/privacy/idempotency context annotations cannot carry.

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?

Front-loaded with the action and parameter bounds, followed by opt-in consequences and a clear WRITES warning. Dense but every clause carries information; the parenthetical bucket list is long but functional.

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 mutation tool with no output schema, the description covers behavior, privacy exposure, and write semantics thoroughly. The remaining gap is the undocumented 'secret' parameter, which an agent must guess at.

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 50%: interval_seconds already documents '60 to 604800, or null to withdraw', which the description essentially repeats, while the second parameter (secret) is unexplained in both places. The description adds the meaning of null (withdraw) but does not compensate for the undocumented secret parameter.

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 description gives a specific verb and resource ('Declare how often you mean to check in') with the exact parameter range and the null-withdrawal case, so the operation is unambiguous. It does not explicitly distinguish itself from neighbors like me, pulse, or checkpoint_crank, but the cadence-declaration scope is distinct enough to identify.

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 states both use modes clearly: set an interval (60–604800) or pass null to withdraw, and explains the opt-in consequence of declaring. There is no explicit when-not-to-use guidance or named alternative tool, so it stops short of a 5.

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