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

Even with annotations present, the description adds meaningful behavioral detail: daily re-check cadence, email-only-on-change, idempotent subscriptions, unsubscribe semantics, storage of normalized target and HMAC, and the verdict-change rule. It also correctly complements `idempotentHint: true` by saying 'Asking twice is idempotent.' No contradiction with annotations.

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?

The description is well-structured with labeled sections and front-loads the decision-relevant 'USE WHEN' and 'WHAT HAPPENS' content. It is longer than strictly necessary, with the pricing sentence and 'No price is quoted here' adding little to tool invocation, but each major section still serves a purpose.

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 tool with no output schema, the description compensates by listing the JSON return fields and providing a concrete example. It also covers privacy, idempotency, and the verdict semantics. Minor gaps remain around failure behavior, rate-limit specifics, and exact delivery timing, but the agent has enough to invoke and interpret the tool correctly.

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 100%, so the baseline is 3, but the description adds useful parameter-level context: normalization of targets, one row per address and target, HMAC-based counting of `notify_to`, and the idempotent/unsubscribe behavior of `action`. The example also demonstrates a valid parameter combination. This goes beyond what the schema alone states.

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 opens with a specific conditional purpose: use when an agent wants to be told if something 'stops checking out' rather than re-running Preflight itself. It names the watched resources (repo, package, endpoint, agent) and the core behavior (daily re-check, email only on verdict change), which clearly distinguishes it from the preflight and change-listing siblings.

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 an explicit 'USE WHEN' condition and contrasts the tool with re-running Preflight on a schedule. It also states clear exclusions: 'Never on a schedule, never a digest', and that transitions into `unknown` are not mailed, so an agent knows the exact conditions under which this tool is or is not appropriate.

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