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

Annotations already declare this is a non-read-only, idempotent, non-destructive, closed-world operation; the description goes well beyond them by disclosing watch duration (30 days), what gets monitored, the daily re-check cadence for page/MCP checks, and that it is free during early access. It does not say what happens at expiry, whether a watch can be cancelled, 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?

Three sentences ordered as trigger, behavior, then terms (duration, input, cost), so the critical usage condition lands first. Slight informality ('Free during early access') and the parenthetical example list add length without much decision value, but nothing is wasted enough to harm usability.

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 subscription tool with no output schema, the definition still covers when to call it, what the watch covers, how long it lasts, and cost. The notable gap is that no output schema exists and the description does not indicate what is returned or how the watch's findings are later retrieved.

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?

The single parameter is already fully documented in the schema, including its rcpt_... format and origin. The description confirms only that the receipt_id is the sole input and extends the provenance to verify_page and verify_mcp results, which is marginal added meaning. Baseline 3 is appropriate given 100% schema coverage.

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 states a concrete verb+resource (place a watch on a decision) and spells out what is actually monitored: records, manufacturer sources and US recall notices for product decisions, daily re-runs for page/MCP checks. It also anchors itself to the sibling flows that produce the receipt (compatibility check, purchase plan, verify_page, verify_mcp). 'Watch' alone is slightly ambiguous about whether it creates a subscription, but the body resolves that.

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 trigger condition is explicit and front-loaded: call this when the preceding result is something someone will rely on later, with concrete examples (an order next week, an install, a resale, an agent handoff). There is no explicit when-not guidance or contrast with decision_status, so it falls short of a full 5.

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