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

Annotations only carry destructiveHint=true; the description goes well beyond that by flagging irreversibility, the exact response shapes for both success and no-op cases, the post-hoc remediation ('if it was already read, the recipient has the value, so rotate the credential'), the creator-only auth requirement, and that the call is free.

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 verb and consequence, and every clause earns its place given the absence of an output schema. The no-op return path is a dense run-on sentence, but it carries genuinely necessary information.

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?

With no output schema and minimal annotations, the description compensates fully: it documents both success and no-op responses, states the irreversible mutation, and identifies the required credential source, leaving nothing an agent needs before calling it.

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%, so both parameters are already documented. The description restates the receiptToken constraint ('only works for secrets you created (needs their receiptToken)') but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 and resource ('Permanently destroy an unread secret you created') plus the observable effect ('its link stops working'), which cleanly separates it from ncrypted_create, ncrypted_read, and ncrypted_status.

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?

Gives concrete situations for invocation ('sent to the wrong place or is no longer needed') and a hard restriction ('Only works for secrets you created'), but never names the sibling tools an agent might otherwise reach for, so the when-not is implied rather than routed.

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