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

readOnlyHint=true is consistent with a status check, so no contradiction. The description does add real value beyond the annotation by enumerating the four possible lifecycle states and noting the call is free, but it says nothing about how the receiptToken is validated or any rate/abuse limits on the lookup endpoint.

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 compact sentence that front-loads the core action, with the state list inline and the cost hint ('Free') at the end. Nothing is wasted, though the trailing fragment could have been folded in more smoothly.

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 read-only tool with no output schema, the description covers the conceptual return values (the status set) adequately, but omits any explanation of the required receiptToken and how to obtain it, which is the main gap for correct invocation.

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 0% and neither property has a description. The description only loosely implies what 'id' is ('a secret you created'); the required 'receiptToken' — a security credential — is never mentioned or explained, so the description does not compensate for the coverage gap.

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 ('whether a secret you created has been read yet') and enumerates the possible states (pending, read, burned, expired), which clearly separates it from ncrypted_read (fetch content) and ncrypted_burn (destroy). It never names those siblings explicitly, so differentiation is inferential rather than stated.

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 phrase 'a secret you created' implies the caller must be the creator, and 'Free' hints it is the cheap option for polling before a read, but there is no explicit when-to-use / when-not-to-use guidance or named alternative such as ncrypted_read.

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