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

Annotations already declare readOnlyHint=true, openWorldHint=true, non-destructive and non-idempotent, so the safety profile is covered; the trailing 'Read-only' is largely redundant. The description does add genuine behavioral value by enumerating the four possible outcome states, which is important context with no output schema. 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?

Three short sentences, front-loaded with the core action, then the interpretive rule, then the safety note. No padding and nothing that fails to earn its place.

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 single-parameter read tool with no output schema, the description usefully compensates by naming the returned states. It stops short of describing staleness, caching, or timing behavior, but nothing essential to invoking the tool correctly is missing.

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% for the single checkout_id parameter, including its pattern, so the schema carries the semantics. The description adds nothing about the id format or origin beyond what the schema's own description already states, making baseline 3 appropriate.

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?

States a specific verb ('Check') and resource ('a checkout created by this connector'), and enumerates the exact states it can return (awaiting payment, paid, processing, expired). This cleanly separates it from sibling status tools like get_crowdfund_status and get_result without needing their schemas.

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 line 'Report "paid" only when this returns paid' is an explicit interpretive rule telling the agent not to infer payment from other signals. It gives clear usage direction but never names the alternative sibling tools or the conditions under which they would be preferable.

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